False Widow Spiders of the UK

Latrodectinae - A subfamily within the Comb-footed Spider family Theridiidae (pronounced "Thair-rid-eye-idd-ee"), that consists of the medically significant Latrodectus, Widow spiders, the Steatoda, False Widows and the Crustulina genus.

False Widow Spiders

The term "False Widow Spider" is a colloquial name used to describe all spiders within the Steatoda genus, several of which are found in the UK. Each of these spiders bears a visual resemblance to the notorious Black Widow Spiders, to varying degrees. Scientific literature dating back as early as the early 1900's use the term "False Black Widow" to describe the species Steatoda grossa, so it's certainly not a new name invented by the media, as you will often hear members of online wildlife groups incorrectly claim. The term was more suitably reduced to "False Widow" to describe Steatoda nobilis, as this species never has a black abdomen, although dark brown specimens can be found. The topic was discussed on the Spider ID Facebook Group with excellent research by Martin Bell, who found an early reference to Steatoda grossa as the False Black Widow from the "Bulletin of the New England Museum of Natural History" Volumes 49–88, dating back to 1928. LINK LINK 2

The term "False Widow" is actually highly suited to these spiders. The term recognises the strong visual similarity between some Steatoda species and Latrodectus species of Black Widows. The term "False Widow" also clarifies that Steatoda species are not members of the far more venomous Latrodectus genus but do share other similarities that go way beyond that of just superficial appearance. There are even similarities between the more extreme, but rare, symptoms of steatodism and the more dangerous, and common, symptoms of latrodectism. In the UK we tend to use the term "False Widow" to describe species of the Steatoda genus, but in N. America, where they have both Steatoda and Latrodectus species, the term "False Black Widow" is still the regularly used common name for Steatoda grossa.

There are six different species of False Widow that are found in the UK. Each of these False Widows has its own common name. Three species are common and widespread, the Noble False Widow (Steatoda nobilis), the Cupboard Spider (Steatoda grossa), and the Rabbit Hutch Spider (Steatoda bipunctata). We also have two smaller, rarer species that are found mainly on heathland, the White-Spotted False Widow (Steatoda albomaculata), and the Heath False Widow Spider (Steatoda / Asagena phalerata). Finally there is the Triangulate Cobweb Spider (Steatoda triangulosa), that's established around various garden centres and nurseries in the UK, and is believed to be an imported species. There is also the Mediterranean False Widow (Steatoda paykulliana), that turns up in the UK fairly regularly as an accidental import amidst imported fruit, usually grapes from the Mediterranean. However, Steatoda paykulliana is not established anywhere in the UK and is only found as isolated specimens, usually hidden amidst imported goods. The most venomous species in the UK, and the one most often referred to as the False Widow Spider by the British media, is the Noble False Widow Spider, Steatoda nobilis.

Both the Black Widow Spiders (Latrodectus species) and the False Widow Spiders (Steatoda species) belong to the family Theridiidae. Theridiids are often referred to as comb-footed spiders, because of the comb-like rows of curved bristles on the tarsi (feet) of the rear pair of legs. They are also known as cobweb spiders because of their messy and irregular webs. As of 2018 there are around 120 recognised Steatoda species found throughout the world. See list here: LINK, World Spider Catalogue

Noble False Widow - (Steatoda nobilis)

The Noble False Widow was first recorded in the UK, as a single specimen, in Torquay, back in the late 1860's or early 1870's. The spider wasn't identified though until some years later in 1879. There is some question over the accuracy of this record though because the original specimen was kept in a collection of spiders, including some possibly collected from Madeira, and not identified until several years later by another arachnologist. It wasn't until 1906 when the next Noble False Widow was found in the UK, on a cliff in southern England. The Noble False Widow is believed to have been accidentally imported into the UK from the Canary and Madeira Islands, amidst crates of fruit, probably bananas.

Although Steatoda nobilis has been occasionally recorded in the UK for over 150 years it didn't really get a strong foothold here until around 1984-1986, when large populations of Steatoda nobilis were recorded in Portsmouth. Steatoda nobilis was confined to the south of England for a further 25 years, with very little indication that it was spreading. It was only since about 2010 that Steatoda nobilis really started to rapidly extend its range and spread further north up the country. Steatoda nobilis wasn't just spreading in the UK at this stage either. Steatoda nobilis suddenly showed up in the USA in large numbers in 2012. By 2014 Steatoda nobilis were also present in South America. By 2018 Steatoda nobilis had turned up in much of Europe too. It's not known what triggered this adaptation and ability for Steatoda nobilis to suddenly, and drastically, increase its range and begin spreading across the world.

Steatoda nobilis are now regularly seen in houses and gardens across much of England. In fact in recent years Steatoda nobilis have now become one of the most common species to be found around many homes in the southern half of the country. There is growing concern that nobilis may now be having a negative effect on native species by out-competing and displacing other spiders. Some scientists and arachnologists are now calling Steatoda nobilis one of the most invasive species of spider in the world.

Noble False Widow Spiders are the largest of the false widow species in the UK, with females usually growing to a maximum body-length of around 8-11mm for females, with some specimens reaching up to 15mm, and a leg-span of 30-35+mm. Males typically reach around 7-10mm body-length, but unlike most other Steatoda species, the male Noble False Widow can be just as large, or even larger, than the female. Steatoda nobilis have recently received great interest from the British press and are often reported as being aggressive, dangerous, highly venomous and deadly. Although Steatoda species are capable of delivering a moderately painful bite to humans none of the many specimens that I have ever captured and photographed have ever exhibited any defensive behaviour beyond either playing dead or trying to run away. They can move at a fair pace in short bursts but generally I have found them to be a very docile and slow moving species of spider.

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Travis McEnery discusses the history of Steatoda nobilis in his excellent video - LINK

Despite being in the UK for over 140 years the Noble False Widow Spider has recently gained a pretty bad, and probably undeserved, reputation, which has been generated by sensationalized stories in the media, such as these examples during 2014:

"False Widow Spider ate my leg!" "False Widow Spider bites teen in cinema" "Flesh-eating monsters are still here" "False Widow Spider ate my foot"

"False Widow Spiders are eating Dad alive" "False Widow Spider bite could kill" "Killer spiders ate my leg" "False Widow Spider made my leg explode"

"False Widow Spiders attacked my little girl" "50 False Widow Spiders invade home" "Killer Spiders invade Britain" "False Widow Spiders close school"

These stories are usually highly exaggerated and based on little fact. Rarely has the accused spider been caught for a positive identification, and severe reactions from bites are often the result of infection, either by bacteria from the fangs of the spider itself, but sometimes the result of a secondary infection introduced by the victim scratching the bite with dirty hands. However many scientists are now concerned that the Steatoda nobilis may be of more concern to humans than initially thought, and claimed, by arachnologists. In 2020 Clive Hambler wrote a paper entitled "The 'Noble false widow' spider Steatoda nobilis is an emerging public health and ecological threat.". In this thought-provoking, and lengthy paper Hambler suggests many of his own theories and concerns and on page 29 wrote the following statement aimed at arachnologists, and the B.A.S. in particular:

"I argue that the British Arachnological Society guidance (B.A.S. 2019b, 2019c) on "false widow spiders" (all Steatoda species) needs substantive revision, both in terms of the likelihood of bites and the severity of effects. I disagree that "False widows are sedentary by nature, remaining in their webs". Nor do I agree that "the risk of being bitten by a false widow spider must surely be relatively small". I argue the statement that S. paykulliana "can deliver a painful bite but the venom is quite mild in its effect" should be revised in the light of the experimental studies on mammals (Maretić 1978a). I argue it important not to either overstate or neglect the risk a Steatoda bite poses, and that all bites by Steatoda species should be treated in a similar way until any species-specific variation is identified."

5mm sub-adult male Noble False Widow, found in my SE London home, 17th October 2013.

Until Steatoda nobilis are close to reaching maturity the shape of the abdomen can't reliably be used to determine the sex. This 5mm specimen is a young male Steatoda nobilis, that I photographed over 10 years ago. As you can tell the palpal bulbs at the tips of the pedipalps already identify this as a male, and yet the abdomen is still large and bulbous as you would expect to see on a female specimen.

Are False Widow Spiders dangerous?

With all the negative attention from the media in recent years are Steatoda nobilis really a danger to humans? There is some debate over whether Steatoda nobilis should be classed as "of no medical significance to humans" or "of minor medical significance to humans". The simple answer is bites from Steatoda nobilis aren't usually of any real concern to humans but they can be very unpleasant. False Widow Spider bites are fairly rare. Studies have shown that 88% of bites happen either at night, when the victim is sleeping, or when the spider becomes trapped in clothes against human skin. The Noble False Widow Spider is usually a slow moving and fairly docile species that is often very reluctant to bite humans, and will usually only do so if they feel threatened, they're sat on or laid on, or they become trapped between clothes / bed sheets and human skin. The media do a great job of vilifying our wildlife as fear sells newspapers and generates online "clicks" unfortunately. Schools have even been closed down because False Widow Spiders have been found within their grounds and parents have overreacted and demanded action be taken. The truth is, if people looked hard enough then these spiders could almost certainly be found in almost every single school in the southern half of the UK. Due to their ability to adapt to various habitats Steatoda nobilis have now become one of the most commonly encountered species of spider to be found around homes, and other buildings, in the UK, especially in the SE of England, and yet bites are still fairly uncommon.

Whilst Steatoda species are generally not considered to have a bite of any medical significance to humans, unlike their far more dangerous cousins from the Latrodectus genus, they share far more similarities than just a superficial visual resemblance. Both Steatoda and Latrodectus species are Comb-footed spiders from the family Theridiidae, and as such both are nocturnal hunters that build messy tangle-webs. Even the majority of the components that make up the venom of both Steatoda and Latrodectus species are extremely similar. Following an extreme envenomation from Steatoda species, which is very rare, the symptoms of Steatodism can be very similar, although far more mild, than the common effects of a bite from Latrodectus species. However the venom of Latrodectus species is far more potent and dangerous to humans. In depth studies on the toxins that make up the venom of Steatoda nobilis and Steatoda grossa have revealed the venom to contain a wide arsenal of active ingredients including latrodectins, α-latrocrustotoxins, CRISPs, α-latrotoxins and δ-latroinsectotoxins. It is the presence of α-latrotoxins that makes the venom most effective against vertebrate victims, and it is these proteins that cause the most pain to humans. - LINK LINK 2

In most cases a bite from Steatoda nobilis is usually considered to be no more painful than that of a bee or wasp sting. Spiders rely on their venom for killing and subduing their prey, and do not want to waste it unnecessarily, so most defensive bites to humans will have little venom injected. The most common symptoms are swelling, and pain at the bite site, which can vary from mild to completely debilitating. More severe symptoms can occasionally occur though and can result in the need for hospitalisation. The more severe symptoms can include severe pain, tremors, itchiness, severe swelling and reddening surrounding the bite area. Very occasionally this can be accompanied by nausea, vertigo, cramps, hypotension, vectored bacterial infections including cellulitis and dermatitis, reduced or elevated blood pressure and possibly even breathing issues. Occasionally localised minor necrosis has also been seen at the site of the bite. The symptoms vary from one person to the next and depend on the victim's age, general health, the amount of venom injected and their sensitivity to the venom. These more severe symptoms are extremely rare and such incidents are more typically associated with bites to very young children, who tend to be more sensitive to the effects of venom. Most severe cases that include severe swelling and ulceration are caused by infection to the wound. Infections can occur either when introduced directly from bacteria found on the spider's fangs or as a secondary infection introduced by the scratching of the bite area. The type of bacteria found on the fangs of Steatoda nobilis can be highly resistant to antibiotics, so infections caused by a defensive bite could be slow for the patient to overcome. Minor symptoms usually disappear within 3 days. If symptoms persist or are severe then medical assistance should be sought without delay as medical treatment, including antibiotics, may be needed. Excessive swelling or reddening of the bite area could be indications of an infection in which case medical attention should be sought as early treatment with antibiotics will be more effective at fighting any infection. In all cases wounds should be cleaned and a disinfectant applied to reduce the risk of infection. An ice pack may be applied to reduce swelling and pain. Avoid scratching or rubbing the bite area as again this will increase the risk of infection and exaggerate the body's reaction to the envenomation. Antihistamines often help to reduce the body's reaction to spider and insect bites.

Steatoda nobilis and Bacteria

It's important to keep things in perspective. In the UK an average of 3-10 people die every year as a result of being attacked by dogs, and yet dogs are commonly kept as pets. In the UK alone an average of 2-9 people die every year after experiencing an anaphylactic reaction to a wasp or bee sting. And yet here are no confirmed records anywhere in the world of anyone ever dying as a direct result of being bitten by any False Widow Spider. Although some people, especially very young children, or the elderly in poor health, may be more sensitive to spider venom, there are currently no confirmed records of any anaphylactic allergic reactions following a bite from any wild spider in the UK.

Whilst there is little reason to fear False Widow Spiders, or any spiders found in the UK, if you need to relocate a spider then it's always best to avoid free-handling spiders and catch spiders using the "glass and card technique", to avoid accidentally harming the spider or risking harm to yourself.

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In In recent years specialist researchers, including Dr John Dunbar, at the Venom Systems and Proteomics Lab at NUI Galway’s School of Natural Sciences, have been collecting specimens and data since 2016 for research on Steatoda nobilis. It'll be interesting to see the results of these studies in upcoming years and read how the recent expansion of the range of Steatoda nobilis in the UK is affecting other native species and read the conclusions of the effects on Steatoda nobilis bites to humans.

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The early results in 2020 of J P Dunbar's analysis of Steatoda nobilis venom has revealed an alarming level of similarities in the make up of the venom of Steatoda nobilis and that of the closely related, and far more dangerous, Latrodectus species of Black Widow spider. LINK LINK 2

Are Steatoda nobilis a danger to native species?

There is growing concern that Steatoda nobilis may now be having a negative effect on native species by out-competing and displacing other spiders. Steatoda nobilis have an excellent tolerance to cold weather and can still be active when temperatures are around zero degrees, and too cold for most native species to be active. Steatoda nobilis also live longer than many native species and can sometimes exceed more than five years of age. Steatoda nobilis has been proven to have a more potent venom than any of the native species that have been studied. In fact recent studies on the venom of Steatoda nobilis have shown that it can be as high as 230 times more potent than the venom of the Lace Web Spider, Amaurobius similis, and 125 times more potent than the venom of the Giant House Spider, Eratigena atrica, both being synanthropic species of spider which Steatoda nobilis competes against around houses in the UK. Steatoda nobilis can reproduce at a very high rate, with multiple egg-sacs being produced each year, up to 18 months or more after copulation. Dr JP Dunbar's studies on Steatoda nobilis in Ireland proved that Steatoda nobilis can produce egg-sacs as often as every 3-4 weeks between April and September each year. The egg-sacs usually hatch after around 3-4 weeks but egg-sacs produced late in the autumn might not hatch until the weather warms up, several months later. This species is also proving to be highly adaptable to various habitats. With all these strengths combined Steatoda nobilis is a serious competitor when up against our native spider species and one I believe is likely to be a serious threat.

In my own town, in SE London, the Rabbit Hutch Spider, Steatoda bipunctata, hasn't been seen for several years. I have to drive about 10-15 miles away from London before I start finding this species again. The disappearance of Steatoda bipunctata in my area is in my opinion a direct result of the non-native Steatoda nobilis out-competing and displacing this smaller species. Stuart Hine, who lives in Reading and who formerly worked at the Natural History Museum, made the following comments on the British Spider ID Group, on Facebook, when discussing Steatoda bipunctata: "Haven’t seen one in the garden for more than 8 years … not since the nobilis mobsters moved in. We’ve also lost Nuctenea umbratica in the garden."

JP Dunbar Studies 2022

As part of the ongoing studies on Steatoda nobilis by Dr J P Dunbar, and his team at Venom Systems and Proteomics Lab at NUI Galway’s School of Natural Sciences, his latest scientific paper entitled "High Venom Potency and Ability to Optimize Venom Usage Make the Globally Invasive Noble False Widow Spider Steatoda nobilis (Thorell, 1875) (Theridiidae) Highly Competitive against Native European Spiders Sharing the Same Habitats" was published on August 26th 2022. The released of the paper was also covered by the Irish Times.

This excellent study has revealed just how successful Steatoda nobilis has become in recent years, with the paper referring to the species as "globally invasive". Steatoda nobilis has been shown to have the most potent venom of any spider species in northern Europe. The spider has the ability to optimise the use of this potent venom by injecting just the right amount needed for each application. Usually after feeding, or using their venom in defensive bites, most spiders can be vulnerable to attack when they've depleted their venom reserves. By using just a tiny amount of their highly potent venom reserves for each application Steatoda nobilis are able to avoid leaving themselves vulnerable to attack from other predators. And when Steatoda nobilis do find themselves in a situation where their venom reserves are running low studies have shown they are able to adapt to a variation in hunting methods to best utilise their remaining venom. It has been shown that Steatoda nobilis utilises silk flicking, and prey wrapping, prior to attempting envenomating bites. This not only serves as an effective means of venom conservation but also helps Steatoda nobilis avoid being bitten or stung by its prey.

Is it just female Steatoda nobilis that can deliver a painful bite to humans?

Studies have shown that their is no variation between the venom yield or potency of male and female Steatoda nobilis specimens. In fact it is male specimens that typically leave their webs and go wandering around human homes in search of female mating partners. With 88% of bites happening either at night, when the victim is sleeping, or when the spider becomes trapped in clothes against human skin, it is reasonable to conclude that most clashes between humans and Steatoda nobilis, that result in bites to humans, will come from male specimens. Tests have also revealed that the size of a Steatoda nobilis specimen does have a direct correlation with the extent of its venom yield, with larger Steatoda nobilis being able to deliver a far more venomous bite than smaller specimens. This has also been found to be true with many other species of spider. Unlike many other spiders though, especially those from the Steatoda genus, male Steatoda nobilis can be just as large, or even larger, than their female mating partners. Time of year was also found to have an affect on venom yield, with the venom yield of Steatoda nobilis found to be considerably higher in the autumn months than during the summer. Due to the α-latrotoxins present in the venom of Steatoda nobilis this species has been able to expand its diet to include small vertebrate prey, such as bats and lizards, as well as other invertebrates. Steatoda nobilis is also able to tackle additional prey outside of the usual diet of other species of spider. In southern California, USA, Steatoda nobilis has been observed preying on the Milkweed Bug, Lygaeus kalmii kalmii, which is noxious and avoided by many predators, including other Steatoda species.

Surprisingly the venom of Steatoda nobilis has been shown to be even more effective at quickly paralyzing some invertebrate prey than the potent venom of Latrodectus species of Black Widow.

8mm sub-adult female Noble False Widow Spider that still has its striped legs and doesn't yet have the black cephalothorax (upper body / head).

Steatoda sp. feeding on vertebrate prey

On August 10th 2021 Ben Waddams, wildlife artist and wildlife film presenter, posted images on Facebook of a Noble False Widow Spider feeding on a Pipistrelle Bat. The Steatoda nobilis had caught a small bat pup in its web and was observed feeding on the young bat several nights in a row. Whilst the wrapped bat pup was still hanging in the web a second bat, this time an adult Pipistrelle Bat, was also caught in the web. On the second occasion Ben released the bat from the web unharmed before the spider could inflict any bites. It's not sure whether the spider deliberately built its web by the entrance to the bat roost or whether the bats were caught by chance. This is probably the first record of a spider catching mammalian prey in the UK.

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On 8th August 2022 a video was shared to the British Spider Identification Group, on Facebook, that showed a large female Steatoda nobilis hoisting a dead shrew up into its web at the top of a window frame. It's not clear whether the spider actually killed the shrew or if the spider stumbled across a dead shrew and chose to take it back to its web. Was is clear is that Steatoda nobilis, like other Theridiidae, will certainly feed upon mammalian prey when presented with the opportunity.

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On 29th October 2022 'WildlifeLucy' shared a video on Twitter of a Steatoda nobilis that had caught an adult Smooth Newt in its web. The newt continued to struggle in the web for over 12 hours before dying. Although the Steatoda nobilis definitely investigated the trapped newt it's uncertain whether the spider inflicted any bites on the newt or simply waited for the newt to stop struggling before moving in to feed.

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On 4th August 2022, in Chichester, West Sussex, a Steatoda nobilis was recorded feeding on a Pygmy Shrew, Sorex minutus, which it had caught in its web. The Pygmy Shrew is a rare and protected species in the UK.

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Other Theridiidae have also been known to prey on vertebrate species far larger than themselves and hoist the prey up into their webs where they can further entangle their victims and prevent their escape. Hoisting prey above the ground also reduces the risk of the spider having to share its meal with other invertebrate scavengers such as ants. A scientific paper from December 2021, by Dr J P Dunbar and others, reports on Steatoda triangulosa preying on a range of vertebrate prey including Kotschy's Gecko, Mediodactylus kotschyi, European blind snake, Typhlops vermicularis, Texas Blind Snake, Rena dulcis, Wall Lizard, Podarcis muralis, and a Garter Snake, which was 355 times heavier than the spider itself.

A Latrodectus mactan was also shown preying on a Common House Mouse. The paper goes on to reveal state "Furthermore, recent studies demonstrated that α-latrotoxin is in fact present in Steatoda venom." A-latrotoxin is one of the highly potent neurotoxin ingredients in the venom of Black Widow Spiders.

Dr J P Dunbar also makes reference to a previous account of Steatoda nobilis successfully preying on a Viviparous Lizard, Zootoca vivipara.

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10mm sub-adult female Noble False Widow Spider from my garden fence in SE London, 21st September 2017

The abdominal markings of juvenile specimens can look quite different from those markings found on fully developed adult specimens.

Steatoda nobilis or Steatoda grossa?

Although variable in appearance adult Steatoda nobilis can usually be distinguished from the similar Steatoda grossa by their larger size, the uniformly orange / brown legs, often with slightly darkened joints and an uninterrupted dorsal pattern. When the abdominal markings are clear the two species can easily be separated but these markings tend to fade with older specimens, especially females. However, even when only the tips of the abdominal markings remain the markings on Steatoda nobilis tend to start closer to the front of the abdomen than those of Steatoda grossa. The legs of nobilis are slightly more robust than those of grossa, but this isn't always an obvious feature. Steatoda grossa often have slight stripes on their legs even on mature specimens. The two share different habitats too with Steatoda grossa preferring much darker habitats to nobilis. Both Steatoda nobilis and Steatoda grossa usually have a pale crescent on the front of their abdomen, but this light band does not extend nearly as far around, or as low down the abdomen on Steatoda grossa as it does with Steatoda nobilis. On darker specimens of Steatoda grossa this crescent is often completely absent.

11mm female Noble False Widow Spider

9mm male Noble False Widow Spider 27th May 2017

12mm female Noble False Widow Spider 17th April 2018

12mm female Noble False Widow Spider, found on the underside of the dustbin lid in my SE London garden, 4th April 2023

Three combined images of a female Noble False Widow Spider photographed in its web by the front door of my home in SE London, 26th November 2020.

Here's an old friend that was always waiting to welcome us home every night. This female False Widow Spider (Steatoda nobilis) lived in a small hole on the white UPVC door frame of our front door for several years. Although False Widow Spiders have been recorded living for over five years it's possible that as soon as one specimen dies this idyllic spot is quickly reinhabited by another waiting suitor.

3mm sub-adult Steatoda nobilis found crawling on my chest in my SE London home. 23rd October 2021.

On 23rd November 2021 I searched a residential garden in Gravesend, in North Kent, at night in the hope of finding Steatoda bipunctata. This was the closest residential address to my SE London home where I had previously found Steatoda bipunctata. Unfortunately I was unable to find a single specimen of S. bipunctata but I did find 36 Steatoda nobilis specimens in that garden. This further supported my beliefs that Steatoda nobilis is displacing native species of spider.

Female Noble False Widow Spider photographed in its web by the front door of my home in SE London, 26th November 2020.

Female Noble False Widow Spider

False widow webs are a messy tangled scaffold of silky threads. The Noble False Widow Spider is primarily a nocturnal species and at night can often be spotted hanging upside down in its messy hammock style web. During the day the spider usually hides away in a crack or crevice in the adjoining wall or fence, or under leaves of vegetation.

Female Noble False Widow Spider

The much maligned Noble False Widow Spider (Steatoda nobilis) hanging in its web in my SE London garden 4th July 2021. I must admit that this one does look mean it the photo and the reflections of my flash on its fang casings give the impression of a sinister expression. The reality is these are a docile and slow moving species out of their web and are reluctant to bite.

Female Noble False Widow Spider, photographed in my SE London garden, 8th August 2021

Sub-adult male Noble False Widow Spider, Steatoda nobilis. One of over 50 specimens counted in my SE London garden in one evening, 14th May 2022.

Sub-adult male Noble False Widow Spider, Steatoda nobilis. One of over 50 specimens in my SE London garden 14th May 2022.

This sub-adult male specimen was almost adult size. When viewed from above it looked very much like an female specimen. However the large rotund abdomen of the female is also often seen on juvenile and sub-adult male specimens too. When viewed from underneath the slightly bulbous tips of the male Steatoda nobilis are clearly visible. This is why it's important to see the tips of the pedipalps to correctly sex a sub-adult specimen. However, once the legs become uniform in colour, and carapace turns very dark black, the shape of the male abdomen is usually less "globular" and is often a good indicator of the sex, if you can't see the pedipalps. The wider carapace is also another indicator of a male specimen.

Noble False Widow Spider, Steatoda nobilis. One of over 50 specimens in my SE London garden 14th May 2022.

Male Noble False Widow Spider, Steatoda nobilis. One of over 50 specimens in my SE London garden 14th May 2022.

Female Noble False Widow Spider, Steatoda nobilis, on the garden fence in my SE London garden 27th August 2022.

Male & sub-adult female Noble False Widow Spiders, Steatoda nobilis. One of over 50 specimens in my SE London garden 14th May 2022.

Mating, and mate-guarding

This photo shows a male and a sub-adult female Steatoda nobilis sharing the same web. They were seen in the web together every night of the week before this image was taken. This behaviour is known as mate-guarding. The adult male Steatoda nobilis has found an immature female specimen that isn't too far from reaching maturity. The male will safeguard the sub-adult female from rival males, until she reaches maturity and is able to copulate. This is the best way to ensure that the male will be the first to mate with the female once she matures, and the most likely to have his sperm fertilise the majority of the female's eggs. Once the female matures the male will usually mate with her several times before heading off to look for another female. Unlike many species the female Steatoda nobilis will not usually show any aggression towards the female, even after mating has occurred.

With many species of spider there's quite a difference in size between the male and female specimens, with females usually being considerably larger than the males. Even with most Steatoda species, such as Steatoda paykulliana, there is quite a substantial difference in the size of the sexes, and the females will readily eat male suitors, before or after copulation. Male Steatoda nobilis can often be nearly as large as mature females, or even larger than some adult female and sub-adult specimens. It is quite possible that this similarity in the size of the sexes could be partly responsible for female Steatoda nobilis being far less inclined to view the male as a potential meal than we see with other species. Male Steatoda nobilis also live far longer than most other male Steatoda species too. It would appear that male Steatoda nobilis have clearly evolved to mate with multiple females, rather than dying shortly after copulation, which is often the case with other species. This is very likely to be one of the reasons behind the huge success of this species. Cannibalism does still occur though and it is not uncommon for larger Steatoda nobilis of either sex to prey on smaller specimens. Occasionally adult females will eat male suitors, before or after copulation takes place.

How can we tell this is a male and sub-adult female? The swollen tips of the pedipalps can clearly be seen on the first spider, and are completely lacking on the second, so the sex of both specimens is clear. The female was half the size of an adult specimen. The size, shape, colouration and abdominal pattern of the female's abdomen are also indicative of a sub-adult specimen. The female is still showing the slightly annulated legs of a sub-adult as well. Apart from the palpal bulbs on the male pedipalps, there are other ways to distinguish between male and female specimens. The mature males have a smaller abdomen, a slim and more defined waistline, and a slightly wider cephalothorax. The cephalothorax is black, or very dark brown, on mature males. The cephalothorax on the female is not usually quite as dark, as the males but occasionally it is.

Adult male Noble False Widow, photographed under decking at a cottage in Bodmin, Cornwall, 11th August 2022.

Female Noble False Widow, photographed under decking at a cottage in Bodmin, Cornwall, 11th August 2022.

Sub-adult female Noble False Widow, photographed on school railings in SE London, 14th November 2022.

13mm female Noble False Widow Spider, photographed in my SE London garden, 21st March 2022

This large adult female Steatoda nobilis was so heavily gravid that she could hardly walk. At this vulnerable stage she's easy prey for the Giant House Spiders, Stone Spiders and Cellar Spiders that she shares my garden shed with.

13mm female Noble False Widow Spider, photographed in my SE London garden, 21st March 2022

This image clearly shows the arrangement of the 8 eyes of Steatoda species.

10mm male Noble False Widow Spider, photographed in my SE London garden, 21st September 2022

As seen on this specimen the cephalothorax of an adult male Steatoda nobilis is usually very dark black, and wider than that of the female.

13mm female Noble False Widow Spider, found in my SE London garden, 14th September 2023

This large and beautifully marked adult female Noble False Widow was found at night in its web, on my ivy-covered garden fence in SE London. Due to the size of the abdomen it's likely that this female specimen was gravid. As adult females reach maturity their abdominal markings usually start to fade. It's uncommon for a specimen of this size to retain such vividly marked abdominal patterns, that are more typically seen on an immature specimen.

13mm female Noble False Widow Spider, found in my SE London garden, 14th September 2023

11mm male Noble False Widow, found on the inside wall of an office building in Dartford, Kent, 2nd October 2023

This colourful adult male Noble False Widow, Steatoda nobilis, was found wandering on the inside walls of my office in Dartford, Kent. The level of colouration seen on the abdomen of this specimen is more commonly found on sub-adult male specimens. Usually when mature male Steatoda nobilis are found indoors they are searching for a mating partner. At this stage they focus entirely on the task at hand. Whilst they will still feed if an opportunity presents itself they can go for a long period of time without food or water and their abdomens are very often dehydrated and shrivelled. It's quite likely that this colourful specimen, with its nice plump abdomen, has only recently reached maturity.

11mm male Noble False Widow Spider, found on the inside wall of an office building in Dartford, Kent, 2nd October 2023

10mm male Noble False Widow Spider, found on the inside wall of an industrial building in Peterborough, 20th November 2023.

10mm adult male Noble False Widow Spider, found on the inside wall of an industrial building in Peterborough, 20th November 2023.

10mm adult male Noble False Widow Spider, found on an inside wall of my SE London home at night, 12th December 2023.

11mm adult female Noble False Widow Spider, that built its web above the dining-room windows inside my SE London home. 6th March 2024.

11mm adult female Noble False Widow Spider, from my SE London home. 6th March 2024.

8mm female Cupboard Spider / False Widow Spider (Steatoda grossa)

False Widow Spider / Cupboard Spider (Steatoda grossa)

Steatoda grossa is another of the UK's three common species of False Widow Spider. Steatoda grossa prefers a slightly different habitat to the Noble False Widow Spider. Although both species are generally synanthropic, being found around homes and buildings, Steatoda grossa prefer to reside in dark, undisturbed places, such as sheds and outhouses, under manhole covers, and as the common name suggests, at the the very back of dark, cluttered and undisturbed cupboards in buildings. The messy tangle-webs are usually built close to ground level.

Steatoda grossa have adapted well to the dry conditions of our homes, and can last for months without food or water if necessary. The specimen above was found under a manhole cover above a sewage outlet in my garden in SE London / North Kent. Whilst the conditions within the cupboards and sheds, where Steatoda grossa are frequently found, are usually very dry habitats the Steatoda grossa that live under the manhole cover in my garden show this species can also thrive in this very damp environment too. Because of the dark habitats that Steatoda grossa favour their main food source is often woodlice, that share these habitats.

Female Steatoda grossa have a maximum body-length of around 6.5 - 10mm but the males tend to be slightly smaller and slimmer at around 4 - 7mm. Females can live for 2 - 6 years in captivity, but they often typically only live for around 18 months in the wild. Males usually die after mating. The most distinguishing feature of Steatoda grossa are the two or three triangular or chevron markings on the top of the abdomen, which are not always present on larger, older female specimens. Unlike the abdominal markings of Steatoda nobilis, the foremost light chevron marking rarely touches the light abdominal band at the front of the abdomen. This cream coloured abdominal band, found on both Steatoda nobilis and Steatoda grossa, extends further along and further down the abdomen of Steatoda nobilis than Steatoda grossa. On Steatoda grossa specimens, where the abdominal markings have faded, this cream band usually also disappears. However, it's more common for faded specimens of Steatoda nobilis to still exhibit this cream band to some extent when the rest of the abdominal markings have faded or disappeared. The legs of Steatoda grossa, particularly the front pair of femurs, tend to be slightly thinner on Steatoda grossa when compared to those of Steatoda nobilis. The location of the web is helpful in determining which of the two species a False Widow might be. Steatoda grossa build their webs in dark, undisturbed locations. Steatoda nobilis may also sometimes build their webs in dark places, although more often the web is built where it is at least partially exposed to light, but the spider itself usually remains hidden away until it starts getting dark.

Although widely established across England and Wales, with a scattered distribution in the north of the UK, Steatoda grossa was only first recorded here in the UK at several sites in the south of England, around the year 1900. Although its history before this date is unclear it is likely that Steatoda grossa is not originally native, and like Steatoda nobilis, has been accidentally introduced to the UK. It is widely regarded that for a species to be considered as native it generally has to have been here since the last ice-age, or it has to have become established and naturalised here without deliberate or accidental assistance from humans. It's likely that Steatoda grossa does not fit into either definition and therefore could not be regarded as native to the UK. It would be interesting to see how common and widespread Steatoda grossa was in the UK 75 years ago. It's distribution, like Steatoda nobilis, was probably very patchy and localised, pointing to the likelihood of multiple accidental introductions over the years.

Steatoda grossa was not originally assigned to the Steatoda genus at all. Even literature from the 1970's refers to this species as the large Theridion spider, Teutana grossa. Until Steatoda nobilis was excepted as established in the UK Steatoda genus was regarded as the largest Theridion species found here.

8mm female Cupboard Spider / False Widow Spider (Steatoda grossa)

Although not dangerous, the bite of the Cupboard Spider is known on occasion to be moderately painful to humans, but does not cause long term issues. On very rare occasions a bite can cause steatodism, which symptoms can include the site of the bite to blister and the victim could suffer muscle spasms, pain, fever and sweating. The antivenin for Latrodectus sp. (Black Widow Spider) is known to be effective in treating serious bites from Steatoda grossa.

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2mm Cupboard Spiderling / False Widow Spiderling (Steatoda grossa), found in my understairs cupboard, 19th June 2019.

3mm Cupboard Spiderling / False Widow Spiderling (Steatoda grossa), found wandering on my bed, 11th June 2020.

10mm female Cupboard Spider / False Widow Spider (Steatoda grossa), found under a manhole cover in my garden in SE London, 3rd May 2020.

The markings on the abdomen of Steatoda grossa fade with age and larger female specimens, particularly gravid specimens, can sometimes show no markings at all, such as the specimen pictured above and below. Usually when the abdomen is uniform in colour it is a dark plum or reddish brown colour. Very occasionally though specimens with a bright red abdomen have been observed, as with this specimen here in Crantock, near Newquay, in Cornwall: LINK

10mm female Cupboard Spider / False Widow Spider (Steatoda grossa), found under a manhole cover in my garden in SE London, 3rd May 2020.

7mm male Cupboard Spider / False Widow Spider (Steatoda grossa), found under a manhole cover in my garden in SE London, 3rd May 2020.

10mm adult female Cupboard Spider / False Widow Spider (Steatoda grossa), found in SE London, 16th December 2022.

9mm adult male Steatoda grossa found in my SE London home, 20th August 2022.

10mm female Cupboard Spider / False Widow Spider (Steatoda grossa), found under a manhole cover in my garden in SE London, 18th October 2020.

In addition to this adult female False Widow Spider (Steatoda grossa) there were also several tiny 1-2mm spiderlings on the underside of the manhole cover in my garden. The only other invertebrates I find under this manhole cover are other tiny spiders, and woodlice, so these must form the majority of the diet for these Steatoda grossa.

10mm female Cupboard Spider, Steatoda grossa, with egg-sac, found under a manhole cover in my SE London garden, 9th May2023.

10mm female Cupboard Spider, Steatoda grossa, found under a manhole cover in my SE London garden, 9th May2023.

10mm adult female Cupboard Spider / False Widow Spider (Steatoda grossa), found in SE London, 16th December 2022.

This 10mm adult female Steatoda grossa was found late in the afternoon, on 16th December 2022, sitting in the middle of its web, built in a residential recycling bin in SE London. The evening temperatures were around -5 degrees at that time of year, and the daytime temperature was around the freezing point when this spider was found. As seen with other Steatoda species this Steatoda grossa specimen demonstrates just how hardy and how well adapted Steatoda species are to withstanding very cold temperatures.

10mm adult female Cupboard Spider / False Widow Spider (Steatoda grossa), found in SE London, 16th December 2022.

2 day old Spiderlings of the Cupboard Spider / False Widow Spider (Steatoda grossa), 16th April 2023

The adult Steatoda grossa pictured above, that was taken into captivity in December 2022, produced three egg-sacs at the end of the winter. On 14th April 2023 hundreds of tiny spiderlings emerged and filled the web. They were just a couple of days old when this photo was taken and were only around 1 or 1.5mm in body-length at this stage. As seen with these spiderlings young Steatoda grossa have pale stripes on their abdomen, that run from one side to the other. These stripes gradually fade towards the edges, often leaving just the three indicative chevron markings on the top of abdomen, and the pale band at the front of the abdomen, that are typically associated with this species.

A particularly large adult male Steatoda grossa with a body-length of 9mm and a leg-span of just over 3cm.

This adult male Steatoda grossa was found wandering the walls of my SE London home on 20th August 2022 at around 11:30pm. Whilst small juvenile specimens have been found in my home on numerous occasions this is the first adult specimen that I've encountered in my house. Even without the obvious abdominal markings of this adult male Steatoda grossa this spider could still be distinguished by its long, thin legs when compared to those of Steatoda nobilis. An adult male Steatoda nobilis would also have a very dark black cephalothorax and not the orange cephalothorax seen on this specimen.

9mm adult male Steatoda grossa found in my SE London home, 20th August 2022.

As with all Steatoda species the underside of the abdomen lacks the red / orange hourglass marking usually present on real Black Widows, Latrodectus species.

9mm adult male Steatoda grossa found in my SE London home, 20th August 2022.

9mm adult male Steatoda grossa found in the bedroom of my SE London home, 22nd April 2023.

4mm sub-adult female Steatoda bipunctata, found in a garden in Windsor, 2nd June 2022.

Rabbit Hutch Spider / Common False Widow - (Steatoda bipunctata)

The Rabbit Hutch Spider is often associated with outbuildings, sheds, garages, rabbit hutches and chicken coops. It's not entirely clear whether Steatoda bipunctata is a native species to the British Iles, or one that was introduced here hundreds of years ago, like Steatoda nobilis. Either way these spiders are now common and widespread across the UK. Although it is likely that Steatoda bipunctata may have been displaced in some areas that now support a large presence of Steatoda nobilis, Steatoda bipunctata are still far more common than either S.nobilis or S.grossa in the northern end of the UK. Steatoda bipunctata are smaller than either Steatoda nobilis or Steatoda grossa and have a body-length of around 4-8mm for females and 4-5mm for males. This False Widow is usually characterised by the central stripe that runs down the middle of their abdomen. This stripe is regularly broken, in some cases just a series of dots, and in other cases hardly visible at all. The lighter band that runs around the base of the abdomen is also usually broken or dotted. The Rabbit-Hutch Spider probably gets its scientific name, Steatoda "bipunctata", from the two prominent dimples on its abdomen, usually accompanied by smaller dimples. These dimples, known as the apodemes, are where the spider's muscles and internal organs are attached to the inside of the spider's abdomen. They are found on all spiders, but are more obvious on some species, and some specimens, than others.

With Steatoda nobilis, and Steatoda grossa, the mature males only have subtly swollen tips to their pedipalps. Steatoda bipunctata is quite different in this respect though as the males have lengthy pedipalps and very obvious palpal bulbs, which makes them easy to distinguish from either of the other two species, or from the females, long before they reach maturity. Viewing the underside of the Rabbit Hutch Spider usually makes identifying this species far easier as they often display a distinctive dark marking that resembles the "Alpha" symbol of the Greek alphabet. This is obviously easier to see on lighter specimens. Although considered common and widespread this species took me ten years to find in the SE of England. It is possible that Steatoda bipunctata is being displaced by the larger non-native Steatoda nobilis in some cross-over habitats the species share.

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6mm adult female Steatoda bipunctata, found on one of the huge stones at Avebury Stone Circles, in Wiltshire, 28th June 2022.

Due to its age and gravid state the abdominal markings on this female Steatoda bipunctata have almost completely faded. The feint traces of the central stripe that usually runs down the middle of the abdomen can still just about be seen at the base of the abdomen. If one were trying to identify this specimen from a photo then it might be mistaken for Steatoda nobilis. However, at just 6mm in length an adult female Steatoda nobilis would be twice the size of this Steatoda bipunctata. Steatoda nobilis also have longer legs, in comparison to their body-length, than Steatoda bipunctata. As ever the most defining key feature of this Steatoda bipunctata can be found on the underside of the abdomen, where the faded alpha symbol can still be seen.

In Eastern Canada, where both Steatoda bipunctata and Steatoda borealis are found, the two species can't generally be separated without close examination.

Steatoda bipunctata, egg-sac. Produced in captivity 14th July 2022.

The 6mm adult female Steatoda bipunctata, pictured above, was taken into captivity to photo, and two weeks later produced an egg-sac. The egg-sac was 4mm in size and was suspended in the middle of the spider's web. As with other Steatoda species the egg-sac has a pale pink colouration.

4mm sub-adult male Steatoda bipunctata, found on a garden shed in Gravesend, Kent, 27th June 2021.

This sub-adult male Steatoda bipunctata, pictured above, was a single specimen, found at night, on a garden shed surrounded by 13 Steatoda nobilis. The smooth, unstructured, light coloured pedipalps on this male Steatoda bipunctata indicate that this specimen is not yet mature. The pedipalps of a mature male are black, hairy and sharply pointed.

4mm sub-adult male Steatoda bipunctata

4.5mm adult male Steatoda bipunctata, from the flint wall of an old church at Oare Creek, in Faversham, Kent, 5th January 2023.

4mm sub-adult male Steatoda bipunctata, found on a garden shed in Gravesend, Kent, 27th June 2021.

6mm female Steatoda bipunctata, Kent, 24th September 2022.

A nicely marked 4mm male Steatoda bipunctata, found on the flint wall of an old church at Oare Creek, in Faversham, Kent, 2nd July 2022.

A nicely marked 4mm sub-adult male Steatoda bipunctata, found on the flint wall of an old church at Oare Creek, in Faversham, Kent, 2nd July 2022.

4.5mm adult male Steatoda bipunctata, from the flint wall of an old church at Oare Creek, in Faversham, Kent, 5th January 2023.

Upon reaching maturity their are now obvious changes to the male Steatoda bipunctata. The pedipalps of this mature male are black, hairy, more structurally complex and sharply pointed. The cephalothorax (head and body) have also turned black in colour and the abdomen is now proportionally smaller, in relation to the rest of the spider, when compared to immature male specimens.

4.5mm adult male Steatoda bipunctata, from the flint wall of an old church at Oare Creek, in Faversham, Kent, 5th January 2023.

4.5mm adult male Steatoda bipunctata, 7th July 2023.

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13mm adult female Steatoda paykulliana

Mediterranean False Widow Spider / Eastern False Widow (Steatoda paykulliana)

Steatoda paykulliana is a Mediterranean species of False Widow that's non-native to the UK, but does regularly arrive in the UK, as an accidentally imported species.

Steatoda paykulliana typically grow to a body-length of around 8-13mm for females, and with a leg-span of up to 35mm. Males are usually smaller at 4.5 - 8mm in body-length.

Steatoda paykulliana is a species originating from the Mediterranean, that regularly find its way to the UK hidden amidst imported grapes and other fruit. This species has historically only been found living in the wild on a couple of very rare occasions in England, and this has always occurred during the the warmer months of the year as isolated specimens. These isolated cases are due to Steatoda paykulliana specimens arriving here as an accidental stowaway, usually amidst imported fruit, and then escaping, or being released into the wild by the finder. There is no evidence available to substantiate any claimed reports of Steatoda Paykulliana ever being found established anywhere in the UK.

Steatoda paykulliana is named in honour of the Swedish naturalist Gustaf von Paykull. With its dark black body, and often red markings, this is the species most likely to be mistaken for the far more venomous Black Widow Spiders of the Latrodectus genus, which are also not present in the UK, but do very occasionally turn up in imported goods. The red markings on the Mediterranean False Widow can also be yellow, orange or white instead of red. However Steatoda paykulliana do not possess the red hour-glass marking usually present on the underside of most Black Widow Spiders.

The bite of Steatoda paykulliana, as with other Steatoda species, can be moderately painful, but it is generally regarded to be of little or no medical significance to humans in most cases. Steatoda paykulliana, like other False Widows in the Steatoda genus, are not aggressive and bites to humans are very rare in the Mediterranean countries where Steatoda paykulliana are native. In laboratory conditions, during the 1960's & 70's when such tests were more acceptable, Steatoda Paykulliana have been proven to possess a venomous bite powerful enough to kill small mammals, including mice and even large guinea pigs! (see page 26) LINK. The French INPN (The National Inventory of Natural Heritage) reports that in laboratory conditions Steatoda Paykulliana has been proven to kill adult rats and cause temporary paralysis in rabbits. LINK

Nearly all Steatoda paykulliana specimens that arrive in the UK amidst imported fruit are juveniles. Due to their size it would be much harder for adult specimens to hide undetected. As juveniles the female specimens that arrive in the UK have no chance of turning up here in a gravid state, and therefore cannot reproduce and spread, unless by chance there happened to be juveniles of both sexes accidentally brought into the UK in the same shipment. Juvenile and sub-adult Steatoda paykulliana look quite different to the adult females and have annulated legs, tend to be brown in colour and often have cream coloured markings, making them easier to mistake for other Steatoda species that are established in the UK. The abdominal markings are often referred to as resembling fish bones. As the female spider matures the abdominal markings change and take on the brighter red, yellow, orange or white appearance, as the rest of the spider turns to a very dark black colour. Often pictures of Steatoda paykulliana found in books only show the spider as a fully developed adult female, which obviously looks quite different from the sub-adult specimens that turn up in the UK as accidental stowaways amidst imported fruit. Adult male Steatoda paykulliana can look somewhat similar to sub-adult specimens. Adult males usually have orangey-brown legs, which are notably darkened at the joints, and a dark brown abdomen, which usually still displays the white / cream coloured fishbone markings. The tips of the male's pedipalps are slightly swollen and pointed in shape.

It's often reported that any accidentally introduced colonies of Steatoda Paykulliana would not be able to survive our winters in most parts of the UK, and that this would only change if our winters were to become milder in the future. However Steatoda Paykulliana is winter-resistant and has been found at altitudes of 700m in West Bulgaria, where the winters are quite severe and the snow stays on the ground for some time due to the adjacent low mountains. It seems Steatoda Paykulliana is probably not as adaptable to new and varying habitats though as Steatoda nobilis, which has thrived since being introduced to the UK, and Steatoda Paykulliana requires more specific conditions to successfully breed. Steatoda paykulliana is a xerophile, thermophile species, so it requires warm, dry conditions, and it's not the cold of our winters that would kill it off in the UK, but our country is simply too damp for this species to successfully breed here in the wild.

Where I have found Steatoda Paykulliana, in Cyprus and southern Spain, the conditions were very hot and very dry, and the spiders were found hidden away in darkness beneath rocks on sandy soil at coastal sites. This xerophilic species seems to require hot, dry conditions with low humidity, where it builds its web low to the ground. The most obvious places that would appear to meet its needs would be within human habitations, and yet within its natural range Steatoda Paykulliana is usually found outside of homes. The eggs of Steatoda paykulliana are pale pink in colour and are wrapped up in a white egg-sac. The average number of eggs in an egg-sac is around 65. In their native range the young spiderlings hatch towards the end of summer. The newly emerged spiderlings are orange in colour and often display the pale fishbone markings on their abdomen. They may hibernate during the colder months before maturing at the start of the following summer.

Could Steatoda paykulliana be established anywhere in the UK?

Currently no, Steatoda paykulliana is not established anywhere in the UK and has never been proven to ever successfully breed here either. The only Steatoda paykulliana that have ever been found in the UK have been isolated specimens. Due to the unsuitability of our climate I believe it's fairly unlikely that Steatoda Paykulliana will become established anywhere in the UK in the near future either. However, with Steatoda paykulliana regularly arriving in the UK as accidental imports it's quite possible that at some point in the future Steatoda Paykulliana could well adapt to the wetter climate of the UK, just as Steatoda nobilis has done. If Steatoda paykulliana was able to adapt then and it may eventually find parts of the UK that are suitable to its requirements, allowing it to become established here.

There have been occasional reports of isolated specimens of Steatoda Paykulliana being found living in the wild in the UK in the past. In 2008 the BBC featured an article about exotic spiders in the UK, and when discussing Steatoda paykulliana they had a quote from Stuart Hine, who ran the Insect Identification Service at the Natural History Museum. In the BBC article it was claimed that Stuart Hine reported Steatoda paykulliana were already established here in the UK back in 2008. He reportedly went on to say: "Now we have found it in Plymouth. And it looks as if it is here to stay". LINK, LINK 2. Stuart Hine has since been in touch with me (October 7th 2021) to clarify this situation, and it seems the press misquoted him and got their facts completely wrong. So although the occasional specimens may have been found in the wild here in the UK there is no proof Steatoda Paykulliana have ever become established anywhere in this country. Stuart did have one female Steatoda paykulliana specimen sent to him, that was found in a log pile in a porch from Bedfordshire. It went on to produce a viable egg sack. LINK

There were also some speculative records from Kent, near a fruit import warehouse in 2008. Other sources claim sightings from Dorset, Milton Keynes, Plymouth and Tilbury Docks in Essex. Uksafari.com is one source incorrectly claiming that Steatoda paykulliana is established at Plymouth and Essex. According to Stuart Hine, who investigated the reported colony in Plymouth, sightings there have already been confirmed as a mistaken identification of Steatoda nobilis. The claimed colony at Tilbury Docks was reported to be around the site of a major fruit importer so this case may have been feasible at one time, and a small, short-lived Steatoda paykulliana colony might have existed there at some point in the past. However if any short-lived colonies did become temporarily established in the UK they clearly died off quite quickly. There was a claim of Steatoda Paykulliana having previously become established in a conservatory and outbuildings in Dorset back in 2017. Unfortunately, as with all these reported cases, there was no photographic evidence to substantiate this doubtful report and it could not be confirmed. - LINK In 2017 Stuart Hine did once write "Given the frequency that these come in on grapes from Southern Europe I have no doubt that it's just a matter of time before it becomes established".

It's not surprising that members of the public often confuse the common, widespread, and well established Steatoda nobilis with the imported Steatoda paykulliana, when the media regularly print images of the wrong species to accompany their news stories. In 2013 The Independent used a photo of a juvenile Steatoda paykulliana with a scare-mongering story they ran on Steatoda nobilis "invading a school" in Gloucestershire. - LINK

I'd love to hear from anyone who believes they might have any photos of these spiders found at any site in the UK. Please get in touch with a photo. email

11mm adult female Mediterranean False Widow Spider (Steatoda paykulliana)

This female specimen has an unusually shrivelled abdomen due to having just produced an egg-sac, which she was guarding when I found her under a large rock in Paphos, Cyprus. These spiders can have a red, yellow or white band around the abdomen. Sometimes they display a midline pattern on their abdomen which can consist of a stripe or a series of triangles or chevrons. In their native countries the Mediterranean False Widow Spider is usually found low to the ground in dry and semi-dry environments with sparse vegetation. Ideal sites include dunes, moors and heathlands, where they are usually found in cracks in walls or under rocks. Other places where Steatoda paykulliana are frequently found include log piles and disused mammal burrows. Mature females usually produce several large, creamy white, fluffy egg-sacs that are as large as the female herself. - LINK

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5mm juvenile female Mediterranean False Widow Spider (Steatoda paykulliana) found amidst imported Spanish grapes. 6th October 2021.

This Mediterranean False Widow Spider (Steatoda paykulliana) found its way into the UK, as many of this species do, amidst imported white grapes from Spain in October 2021. The grapes were bought in Cornwall by Anne-Marie Young, who very kindly sent the spider to me to photograph and raise. Due to being a non-native species this spider cannot be released into the wild so will now be raised by myself in captivity. LINK This juvenile Steatoda paykulliana specimen is typical in its appearance of others of this species that arrive in the UK amidst imported fruit. Nearly all Steatoda paykulliana specimens that arrive in the UK amidst imported fruit are juveniles and exhibit this dehydrated and underfed shrivelled abdomen.

These photos of this Steatoda paykulliana were posted on Facebook and proved to be one of the most popular posts I have ever shared, with over 500 likes. LINK

Steatoda Paykulliana found in the UK as accidental stowaways.

My research into Steatoda Paykulliana has now found 49 records, which I've been able to confirm as Steatoda Paykulliana, arriving in the UK amidst imported fruit & veg, from 2014 - 2023. Twenty four of these records have come from 2020 and 2021, suggesting that this species may be arriving in the UK more often now than in previous years. The COVID 19 lockdowns of 2020 and 2021 may also have had a significant effect on the number of sightings being photographed and reported, as many people found themselves with more time on their hands during this period. There has also been a huge increase in the number of members of the public joining spider groups on Facebook in recent years, so there is a good chance that the increase in records of Steatoda Paykulliana being found in the UK in recent years is simply because more members of the public now have somewhere to report their finds.

It'll be interesting to see if this current trend continues as society returns to normality, and I'll be keeping a close eye out for new records of Steatoda paykulliana in the UK over the next few years. The most common method of travel appears to be hidden amidst imported grapes, especially those from Spain. One record came from raspberries imported from South Africa, five records came from grapes imported from Greece, one record came from imported bananas, two records came from Spanish pomegranates, and three records came from Broccoli imported from Spain. On 15th June 2022 an adult female Steatoda paykulliana was found at a garden centre in Worcestershire, that arrived with imported plants.

If the number of non-native Steatoda and Latrodectus species being found in the UK amidst imported fruit are on the increase, what are the reasons behind it? One theory, although highly unlikely, and based on a claim by the Daily Mail in a story they ran on 26th November 2002, suggests that these spiders are being deliberately introduced into vineyards as a form of biological pest control to protect the grapes from other insects. LINK. The BBC ran the story the following day claiming that Tesco had strongly denied any deliberate use of Latrodectus species in their vineyards, but admitted that their policy to try and use less pesticides on their fresh produce could result in more spiders finding their way into imports of fruit and vegetables. LINK

5mm juvenile female Mediterranean False Widow Spider (Steatoda paykulliana) found amidst imported Spanish grapes. 6th October 2021.

At 5mm in length this Steatoda paykulliana is quite difficult to identify the sex with 100% accuracy. At this stage both male and female specimens look extremely similar. Females will continue to grow in size and will become very dark black. Females will also lose the annulations on their legs and the abdominal markings will become bright white, red, orange or yellow. Males however, will not usually grow much larger than this at 5mm. Males will usually not change much in appearance either, and will retain this colour, markings, and usually also the annulations on their legs too. The subtly swollen tips to the male's pedipalps will develop as it reaches maturity but are often easily missed when viewed from above.

* I would like to give huge thanks to Anne-Marie Young for sending me this juvenile specimen to photograph, add to my website, and raise in captivity. *

5mm juvenile female Mediterranean False Widow Spider (Steatoda paykulliana) found amidst imported Spanish grapes, 6th October 2021.

Stuart Hine, who previously ran the Insect Identification Service at the Natural History Museum, made the following comments on my images of Steatoda paykulliana:

"The ones I have reared have all lost the fishbone pattern in the last molt, leaving just a silvery band on the anterior of the opisthosoma. As they age this gradually turns yellow to orange and finally red. I’ll be interested to see if you find the same."

9mm female Mediterranean False Widow Spider (Steatoda paykulliana) 26th December 2021.

Photographed nearly 12 weeks after being taken into captivity it is now far easier to determine the sex of this Mediterranean False Widow, Steatoda paykulliana, as a female specimen, with no visible development of palpal bulbs and a large rotund abdomen. During the 12 weeks in captivity this spider has fed well on a once a week supply of flies and mealworms. The body-length has grown from 5mm to 9mm. The previously shrivelled and dehydrated abdomen is now very plump, with a healthy glossy sheen. The abdominal markings have faded from a creamy white colour to a light brown colour. The annulations on the legs are now only just visible.

The spider could reach a final body-length of around 11-13mm. As Steatoda paykulliana mature the abdominal markings typically continue to fade before turning yellow, then orange and finally red. The abdomen and legs will continue to darken and will eventually be completely black. This species does sometimes vary in appearance with its abdominal markings as it matures. Some adult specimens completely lose their abdominal markings when viewed from above and just retain the pale, or coloured band at the front of the abdomen. Other specimens retain some or all of their upper markings as the spider matures and these marking just change colour. The abdominal markings of most female specimens will change from cream / white to yellow, sometimes orange, and then finally red. The markings of some specimens may remain in either white, yellow or orange even once the spider reaches maturity. Some specimens lose all markings entirely and the spider matures to be completely black.

11mm adult female Mediterranean False Widow Spider (Steatoda paykulliana) 9th February 2022

Photographed 4 months after being taken into captivity as a juvenile, this mature female Steatoda paykulliana reached a body-length of 11mm and had completely lost all abdominal markings. The only hint of colour remaining at this stage are the slightly reddish-brown tips of the legs, which also turned completely black within a few weeks of these photos being taken.

11mm female Mediterranean False Widow Spider (Steatoda paykulliana) found amidst imported Spanish grapes 6th October 2021, and raised in captivity 1st May 2022

11mm female Mediterranean False Widow Spider (Steatoda paykulliana) found amidst imported Spanish grapes 6th October 2021, and raised in captivity, 1st May 2022

11mm female Mediterranean False Widow Spider (Steatoda paykulliana) found amidst imported Spanish grapes 6th October 2021, and raised in captivity, 27th August 2022

As with all Steatoda species the underside of the Steatoda paykulliana's abdomen lacks the red / orange hourglass marking usually present on real Black Widows, Latrodectus species.

7mm immature male Mediterranean False Widow (Steatoda paykulliana) found in imported white grapes on 6th August 2021 and raised in captivity. Photos taken13th June 2022.

This male Steatoda paykulliana was found as a juvenile amidst imported white seedless grapes, bought from Asda in Liscard, Wallasey, Wirral, Merseyside 6th August 2021, and possibly imported from Egypt. The spider was raised in captivity by Gemma Madelaine, before being sent to me in June 2022. At this stage this immature male specimen was one shed away from reaching maturity. LINK

* Very grateful thanks to Gemma Madelaine for raising and sending this spider to me. *

7mm immature male Mediterranean False Widow (Steatoda paykulliana) found in imported white grapes on 6th August 2021 and raised in captivity. Photo taken13th June 2022.

In this image you can see the subtly swollen palpal bulbs of the almost mature male Steatoda paykulliana.

8mm mature male Mediterranean False Widow Spider (Steatoda paykulliana) 29th August 2022

This adult male had been in captivity for over 12 months, since arriving in the UK as an accidental import. It was probably 2-4 months old when it arrived here, which means it was likely to be 14-16 months old when it reached maturity. At this stage the spider lost all interest in food and was looking slightly dehydrated and under-nourished. Once mature its primary concern was to mate.

On the first attempt to introduced this male to a mature female specimen the male immediately approached the female in an attempt to mate. Unfortunately despite several approaches from the male the female tried to eat the male on each occasion, and the male was forced to withdraw. The female was then deliberately overfed before any further attempts were made to reintroduce the male again. Unfortunately even once fully fed the female continued to chase off the male whenever he was reintroduced. Sadly the male finally died on 20th September 2022, after refusing to eat since reaching maturity. It never managed to successfully mate with the female. It's believed the male was around 18 months old at its passing.

8mm mature male Mediterranean False Widow Spider (Steatoda paykulliana) 29th August 2022

Female Mediterranean False Widow Spider with Common Green Bottle Fly, 29th August 2022

I began to overfeed the captive female Steatoda paykulliana, before reintroducing the male to reattempt copulation, and the female was given 4 Common Green Bottle Flies, Lucilia sericata, within a 24 hour period. It has been shown in recent studies by Dr JP Dunbar that when hunting Steatoda nobilis utilises silk flicking, and prey wrapping, prior to attempting envenomating bites, especially when tackling larger prey items, or when venom reserves were low. I have observed the same behaviour with captive Steatoda paykulliana. After the female Steatoda paykulliana had consumed 3 Common Green Bottle Flies its venom reserves were obviously running low, as when it tackled the fourth fly it flicked silk, and restrained the fourth fly with partial wrapping, without any attempt to bite the fly. Once the fourth fly was restrained the female Steatoda paykulliana returned to its previous meal, Common Green Bottle Fly number 3.

Female Mediterranean False Widow Spider with Common Green Bottle Fly, 29th August 2022

Female Mediterranean False Widow Spider, 29th August 2022

Female Mediterranean False Widow in foreground, with male in the background, 29th August 2022

This adult female Steatoda paykulliana had been in captivity for 14 months, since arriving in the UK as an accidental import. It died on 25th November 2022. It was believed to be around 17 - 20 months old at the time of its passing. It was feeding well right up until its last day but its abdomen had shrunken in size despite being well fed.

11mm female Mediterranean False Widow Spider with Common Green Bottle Fly, 29th August 2022

In 2016 an adult male Steatoda paykulliana was recorded feeding on a Rough-tailed Gecko, Cyrtopodion scabrum, that it had caught in its web in Iran. There have been several other records of Steatoda paykulliana successfully tackling reptilian prey. LINK

4.5mm juvenile male Mediterranean False Widow, 14th January 2023. (Accidental import specimen 3).

On 11th January 2023 Selena Miller, from Pool in Cornwall, found this 4.5mmsub-adult male Mediterranean False Widow, Steatoda paykulliana, in her fridge. The spider must have arrived hidden amidst imported broccoli, that was purchased and placed in the fridge 4 days earlier, on 7th January. Once removed from the fridge the spider quickly warmed up and became very active once again. This demonstrates the ability of Steatoda paykulliana to withstand pretty cold temperatures. Most imported broccoli comes to the UK from Spain, and is transported in refrigerated trailers. The spider would therefore have already endured very cold temperatures during its journey to the UK. Thankfully the spider was sent to myself in London, where it will be raised in captivity for the remainder of its days. - LINK

* Very grateful thanks to Selena Miller for sending this spider to me. *

4.5mm juvenile male Mediterranean False Widow, 14th January 2023. (Accidental import specimen 3).

4.5mm juvenile male Mediterranean False Widow. Photographed 14th January 2023. (Accidental import specimen 3).

This spider's story was shared in the British Spider ID Group on Facebook - LINK

9mm sub-adult female Mediterranean False Widow, Steatoda paykulliana. Photographed 21st April 2023. (Accidental import specimen 4).

On 16th August 2022 Tina Maria found a very small juvenile Mediterranean False Widow, Steatoda paykulliana, hidden in her imported Spanish grapes purchased from Morrisons in Melton Mowbray, Leicestershire. The spider was then sent to Lorraine Isherwood to be rehomed. Lorraine reared the spider to a body-length of 9mm before it was forwarded on to me so it could be paired with my male specimen. LINK 1 LINK 2 LINK 3

* Grateful thanks to Lorraine Isherwood for sending me this female Steatoda paykulliana. *

9mm sub-adult female Mediterranean False Widow, Steatoda paykulliana. Photographed 21st April 2023. (Accidental import specimen 4).

9mm sub-adult female Mediterranean False Widow, Steatoda paykulliana. Photographed 21st April 2023. (Accidental import specimen 4).

10mm female Mediterranean False Widow, Steatoda paykulliana. Photographed 5th July 2023. (Accidental import specimen 4).

7mm male Mediterranean False Widow, Steatoda paykulliana. Photographed 5th July 2023 (Accidental import specimen 3).

2nd attempt at breeding Steatoda paykulliana in captivity.

Female specimen - Discovered in the UK as a very small juvenile, on16th August 2022, by Tina Maria. Arrived in the UK amidst Spanish grapes.

Male specimen - Discovered in the UK as a sub-adult, on 11th January 2023, by Selena Miller. Believed to have arrived in the UK amidst Spanish broccoli.

My first attempt at pairing accidentally imported Steatoda paykulliana in August 2022 ended in failure. On each attempt at introducing the male the female tried to eat him.

My second attempt with this new pair, in May 2023, was far more successful.

The male hadn't eaten for 6-8 weeks, since reaching maturity. It showed no interest in food at all and would actually run away from any prey I introduced into his enclosure.

The female was a good feeder at this stage and had been deliberately overfed for about a month prior to the male being introduced.

26th May 2023 - I introduced the male to the female's enclosure. For the first 24 hours the male kept its distance and remained at the other end of the enclosure.

27th May 2023 - The male was discovered to be in the web of the female. Both spiders seemed to be embraced, but motionless. At this point I wasn't sure if the female was feeding on the male or not. After one hour the spiders separated and it was clear that both spiders were alive and well. They remained in very close proximity for the rest of the day. By the evening the male had wandered to the edge of the female's web. As I approached to take photos the male rushed back to the female. As the male got close to the female he stopped. The male could clearly be observed twitching his abdomen in small jerky movements. In response the female could be observed stroking her abdomen with one of her rear legs. Steatoda sp. are known to be a genus that communicate via stridulation, and this was definitely was I was observing here. This communication between the pair lasted for 10-20 seconds before the male once again entered the presence of the female. For the next month the pair remained in very close proximity. At night they would both climb up into their joined web. The male would always venture further up the web than the female.

3rd June 2023 - The female's abdomen was still looking nicely plump, having eaten around 8 days before. The male's abdomen was looking very shrivelled and dehydrated, as he hadn't eaten for 7-9 weeks. I lightly misted the web and the male was observed drinking the water droplets. The female wasn't interested. At this stage I was worried how much longer the male would last without food. I was also unsure if mating had actually taken place yet or not. I made some enquiries with Latrodectus keepers and was informed that males usually regain their appetite once mating had occurred. Upon further research I learned that once the female has allowed the male to enter her web, and accepted his as her partner, the male releases pheromones onto the web that usually suppress the female's appetite. This affords the male some degree of protection from being eaten by the female. At this stage the male regains his appetite and once again resumes feeding. The female now loses interest in feeding whilst the male is in the web. Following subsequent breeding of this species I also discovered that weeks after copulation has taken place, as the male nears the end of his natural days, the male may stop releasing his pheromones and actually allow the female to feed upon him. This would ensure the female gets a meal and therefore increases her chances of surviving and successfully raising the male's offspring.

4th June 2024 - Armed with this knowledge, I placed a housefly directly into the web. The male's appetite had definitely returned and the male immediately began wrapping and then feeding on the fly. Thankfully the female didn't react at all and remained motionless whilst the male dined alone on the fly. At this point I was convinced that mating between the Steatoda paykulliana pair had already taken place.

12th June 2023 - I introduced 2 flies into the web. Yet again the male killed and wrapped both flies, whilst the female paid no attention to them.

24th June 2023 - Almost a month after the male and female Steatoda paykulliana were introduced to each other, the female surprised me by shedding her skin. Until that point I had mistakenly assumed that the female was fully mature. Post moulting the female looked no different in appearance.

25th June 2023 - The following day after the female had moulted and reached maturity the male had now moved to the edge of the enclosure, as far away from the female as it could get. I introduced a Blue Bottle Fly to the web and the female immediately attacked the fly and began feeding on it. Now that the male was out of the web the female had immediately regained her appetite. The male remained well away from the female at the edge of the enclosure.

12th July 2023 - After a month since its last meal the male Steatoda paykulliana still refused food and water. At this point its abdomen looked extremely shrivelled and dehydrated. The male continued to stay at the edge of the enclosure, as far away from the female as possible. The female's abdomen remained the same same size with no indication that the spider was gravid. The female now continued to feed at every opportunity.

14th July 2023 - The female left her web and built an adjacent web, where she was fully exposed. The male finally caught, wrapped, and briefly fed on a Greenbottle Fly. It did not feed for long and after briefly feeding its abdomen remained shrivelled and dehydrated. The female continued to feed at every opportunity. During the course of the following week the male entered the female's web and came within about 50mm of the female on a couple of occasions.

21st July 2023 - The male remained at the edge of the enclosure, as far away from the female as possible. He ran away from flies that I attempted to feed him with. The female continued to feed well and remained out in the open in her new web.

24th July 2023 - I awoke to find that almost two months since the male had been introduced to the female's enclosure the female Steatoda paykulliana had now killed, and was feeding on the male Steatoda paykulliana. The male's body was not wrapped in silk at all. This suggests that either he was already weak and unable to struggle, or that he willing entered the female's web and allowed himself to become her next meal for the development of his offspring. At this stage the female's abdomen still showed no signs of being gravid, and at this point it looked unlikely that successful mating had actually occurred at any point since the male was introduced into the female's enclosure, despite the two spiders being inseparable for 4 weeks until the female reached maturity.

6th August 2023 - To my great surprise when I checked on the female Steatoda paykulliana in the afternoon I discovered her guarding an egg-sac! The egg-sac was laid low in the web and measured about 7-8mm across. The male must have mated with the female immediately after she shed her skin and reached maturity. He then either left the web to look for other females or was evicted from the web by the female after copulation had taken place. After producing an egg-sac the female's abdomen was not looking particularly shrunken, or dehydrated, and I believed that further egg-sacs were likely to be produced.

20th August 2023 - Exactly three weeks after the first egg-sac was produced the female Steatoda paykulliana produced a second egg-sac. Over the next six days the female moved and repositioned the egg-sacs at least once a day, and up to three times a day. The egg-sacs have been placed next to one another, above one another, and sometimes separated by a gap of up to 40mm. Following a discussion on the British Spider ID Group we were able to conclude that there were several possible reasons for this behaviour:

Many bird species also turn their eggs regularly. They do this to prevent the embryos from becoming stuck to the membrane on one side of the shell, and to keep the heat inside the eggs even throughout. It also ensures even pressure on the developing chicks within the eggs. In a spider's egg-sac, containing many eggs, turning the egg-sacs would also help to ensure even heat and even pressure on the eggs. It could also help to control humidity and airflow within the egg-sacs. Turning the eggs would help to regulate the light that the eggs are exposed to, which may or may not have an effect on their development. This behaviour is exhibited with other egg producing species too. Shrimps, a swimming crustacean who keep their eggs under their bellies, also regularly juggle their eggs and move them around continuously, to ensure good airflow and prevent fungus from growing on the eggs.

28th August 2023 - The adult female Steatoda paykulliana stopped moving and rearranging the two egg-sacs. They now remain in the same position which could suggest they may be due to hatch fairly soon?

10mm female Mediterranean False Widow, Steatoda paykulliana. Photographed 8th August 2023. (Accidental import specimen 4).

13th September 2023 - I returned home, after a 10 day holiday, to find a third egg-sac had been produced. One of the first egg-sacs had hatched and the adult female's web now contained around 20-25 tiny 1mm spiderlings. This means the spiderlings took 4-5 weeks, or 28-35 days, to hatch and emerge from the egg-sac, since the eggs were first laid.

25th September 2023 - I expected the adult female to show no parental care after the spiderlings emerged from the egg-sac. What I didn't expect was for the adult female to actually defend her meals against any of her hungry offspring that were looking for a free meal. The adult female had a very strong appetite and would immediately pursue any meal that I placed in her web. The tiny spiderlings would instantly be attracted to the struggle that ensued as soon as the female caught her prey. As soon as the prey was restrained the spiderlings would attempt to move in and feed from the wrapped meal. The adult female would defend her meal by kicking any approaching spiderlings away with her front legs. She would do this repeatedly until they all retreated. I began to fear that the spiderlings were not getting adequate meals for them to grow. I then decided to try another approach. I introduced one large fly into the web. As usual the adult female rapidly pounced on the fly and wrapped her meal, and as before the spiderlings were chased away and prevented from partaking of this meal. I left the female biting on the fly, and injecting her digestive enzymes, for around 15 minutes. I then introduced a second large fly to the web. The adult female immediately abandoned her first catch and concentrated on the newly introduced fly. As soon as the first fly was left unattended the spiderlings moved in mass and covered the fly and began feeding. The adult female remained with her second catch and did not return to the first fly, or attempt to stop the spiderlings from feeding from it.

One time when I introduced a second fly into the web the fly remained completely still and the adult female completely ignored this fly. I had to introduce a third fly to distract the female and get her to abandon the first fly for the spiderlings to feed on. However, some of the tiny spiderlings quickly started to learn and once the second, and unnoticed, fly was completely exhausted a couple of the spiderlings moved in and began biting the large fly themselves.

Mediterranean False Widow, Steatoda paykulliana, egg-sacs and 1mm spiderlings. Photographed 25th September 2023. (The offspring of accidental import specimens 3 & 4).

The first image shows the three egg-sacs produced in captivity. Once hatched from their individual eggs the spiderlings remain in the egg-sac until they've shed their skin. Only then will they chew a hole in the egg-sac and enter the web of the adult female spider. You can see in this image that the spiderlings have exited one egg-sac, and the exit hole is clearly visible. You can also see that within the second egg-sac some of the spiderlings have hatched but have not yet exited the egg-sac.

The second image shows the tiny 1mm spiderlings feeding on a housefly that was caught and wrapped by the adult female spider. These two week old spiderlings are reddish-brown in colour with cream-coloured abdominal markings. The abdominal markings are already variable from one specimen to another even at this very small size. Both Steatoda and Latrodectus spiderlings are kleptoparasitic, that is the newborn spiders wait in the web for the mother to catch and wrap prey before attempting to all communally feed on the prey together. Once the spiderlings are a week or two old they will often attempt to share the task of wrapping the prey at the same time as the mother. Sometimes the mother allows the spiderlings to feed on prey she has caught and other times she chases them away until she has fed herself.

2.5 - 3mm, 30 day old, captive-bred Steatoda paykulliana. (specimen CB3-4-7). Photographed 14th October 2023.

13th October 2023 - The spiderlings from the first egg-sac were now 30 days old and had grown to 2-3mm in length. The spiderlings from the third egg-sac were still just one week old and were only around 1 - 1.5mm in length. Cannibalism is common between spiderlings and the larger spiderlings were regularly chasing the other spiderlings around the web. At this stage I decided to remove the 8 largest specimens and keep them in their own pots.

Initially when the spiderlings hatched they had a reddish-brown prosoma / cephalothorax, reddish-brown abdomen with white markings, and reddish legs. After 30 days these spiderlings have the same colouration but the prosoma / cephalothorax had turned black. The legs also started to develop dark annulations / rings.

2.5 - 3mm, 30 day old, captive-bred Steatoda paykulliana. (specimen CB3-4-7). Photographed 14th October 2023.

Accidental import female Steatoda paykulliana (AI4) and 2 - 3mm, 14 -34 day old, captive-bred spiderlings. Photographed 18th October 2023.

Accidental import female Steatoda paykulliana (AI-4). Photographed 18th October 2023.

Accidental import female Steatoda paykulliana (AI4) and 2 - 3mm, 14 -34 day old, captive-bred spiderlings. Photographed 18th October 2023.

6th November 2023 - The adult female Steatoda paykulliana produced a 4th egg-sac. The 4th egg-sac was half the size of the three previous egg-sacs and measured around 4mm in diameter. The female continued to guard, move and rotate this 4th egg-sac just as she had previously done with the previous three.

9th November 2023 - Over the last two weeks the remaining spiderlings were extracted from the mother's web and housed separately. The last two spiderlings were removed and rehoused on this day. The total number of spiderlings from the first three egg-sacs, only two of which were fertile, totalled 31 specimens. Each fertile egg-sac produced around 16-30 spiderlings, which meant that 31 out of the 32-60 spiderlings survived long enough to become independent. This is a pretty good ratio, which would probably be far lower if the eggs were to hatch in the wild. In captivity the spiderlings were given food in abundance so cannibalism was significantly reduced. Being raised in captivity meant the spiderlings were not exposed to extreme weather conditions or the risk of predation from other predators. During the 5-8 weeks that the spiderlings remained in their mother's web at no point did I witness the mother feeding on any of her offspring. She did get annoyed and frustrated by their presence though and would often chase them away from her if they got too close, especially when she was feeding. At 5 - 8 weeks of age the spiderlings ranged in size from 2.5 - 5mm in body-length.

20th November 2023 - The adult female Steatoda paykulliana produced a 5th egg-sac. The 5th egg-sac was around the same small size of the 4th egg-sac and measured around 4mm in diameter. It's unlikely that the 4th or 5th egg-sacs are viable and I suspect that neither will produce any spiderlings.

5th December 2023 - The adult female Steatoda paykulliana produced a 6th egg-sac. The 6th egg-sac was even smaller in size than the 4th and 5th egg-sacs, and measured around 3.5mm in diameter. None of these undersized egg-sacs have produced any spiderlings. I'd always been under the impression that adult female Steatoda species, like many other spiders, can store the males sperm long after mating, and can continue to produce viable egg-sacs for the remainder of their adult lives. With this adult female Steatoda paykulliana producing these micro egg-sacs, which have turned out to be either void of any eggs, or containing infertile eggs, it's as though she has run out of sperm! Knowing how eager larger, and older, female Steatoda paykulliana are to eat their male suitors I decided against risking the introduction another male specimen to her at this time.

11th & 12th December 2023 - A small number of juvenile Steatoda paykulliana were made available to other keepers. - LINK 1 LINK 2

20th February 2023 - The adult female had continued to make small infertile egg-sacs on a regular basis throughout the winter. Finally on 20th February I noticed three newly hatch 1.5mm spiderlings in her web. Clearly one of these micro egg-sacs had contained just a few viable eggs that had successfully hatched.

1st April 2024 - Of the 31 spiderling offspring, from the adult female AI4, I kept 7 specimens back for myself. I kept the largest 7 spiderlings, that also had the boldest and most complete abdominal markings. I did this in the hope of rearing a female specimen that would retain all her abdominal markings into maturity. Unfortunately of the 7 specimens that I held back 6 of them matured to be adult males, around 7 months later. It seems the bolder the markings are on the juvenile specimens the higher chance there is of them being male. With the largest spiderlings all turning out to be male it also seems likely that male spiderlings may grow and develop slightly faster than the females.

Accidental import female Steatoda paykulliana (AI4). Photographed 31st January 2024.

This specimen was probably around 2 months old when it arrived in the UK, as an accidental stowaway back in August 2022. That would make the spider around 1 year and 8 months old when this photo was taken.

Captive-bred sub-adult Steatoda paykulliana (CB3-4-8), 5th February 2024.

This is one of the captive-bred Steatoda paykulliana that came from pairing and mating the two accidental imports, AI3 and AI4. After 5 months since the first egg-sac hatched this 7mm specimen was a sub-adult.

Captive-bred sub-adult Steatoda paykulliana (CB3-4-8), 5th February 2024.

6mm captive-bred sub-adult Steatoda paykulliana (CB3-4-5), 29th February 2024.

6mm captive-bred sub-adult Steatoda paykulliana (CB3-4-14), 29th February 2024.

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Tiny 2.5mm juvenile Mediterranean False Widow, Steatoda paykulliana. Photographed 8th August 2023. (Accidental import specimen 5).

On 04/08/2023 Wendy Simnett, and her partner James Todd, from Great Yarmouth, found a tiny juvenile Steatoda paykulliana in a punnet of Spanish Grapes. The spiderling had a body-length that measured just over 2.5mm. This is the smallest specimen I have seen arrive in the UK, and it did well to survive being kept in a refrigerator. As a non-native species, especially one that isn't established in the UK, the spider could not legally be released into the wild so it was sent to me on 8th August 2023 to be raised in captivity. - LINK

* Very grateful thanks to Wendy Simnett for sending this spider to me. *

Tiny 2.5mm juvenile Mediterranean False Widow, Steatoda paykulliana. Photographed 8th August 2023. (Accidental import specimen 5).

6mm Mediterranean False Widow, Steatoda paykulliana. Photographed 18th October 2023. (Accidental import specimen 5).

Newly shed 8mm male Mediterranean False Widow, Steatoda paykulliana. Photographed 10th December 2023. (Accidental import specimen 5).

This Steatoda paykulliana, accidental import specimen 5, shed its skin on the 10th December 2023 and revealed itself to be a male specimen. Until this point I had mistakenly assumed it was a female. It seems that male Steatoda paykulliana may not always develop any obvious signs of the palpal bulb at the tips of their pedipalps until the later stages of development. A previous male I reared in captivity, Accidental import specimen 3, had very obvious palpal bulbs, and could readily be identified as a male specimen, by the time it was just 4mm in length.

Newly shed 8mm male Mediterranean False Widow, Steatoda paykulliana. Photographed 10th December 2023. (Accidental import specimen 5).

Invertebrates have no inner skeleton to support their body. Instead they have a hard exterior layer of skin, known as an exoskeleton. As the spider develops and grows the spider will periodically shed this old skin, which will be replaced with a new, larger, more developed exoskeleton. When the old skin is shed the new outer layer of skin is soft and offers very little support for spiders. Until this new skin hardens and forms a new exoskeleton the spider may not be able to stand, or even walk, on its new legs. At this stage the spider is very vulnerable to attack from predators. Not only are its legs able to help it escape but its fangs are too soft to be used for self defence too. The spider needs to wait somewhere safe for the new skin to harden before it can move on. This can take anywhere from 30 minutes to several hours. Spiders will often stop feeding in the preceding weeks to shedding their skin. This allows the old exoskeleton to become looser and easier to shed. Once the spider has shed its skin the fangs may take up to a few days before they hard sufficiently to allow them to penetrate the spider's prey, so newly shed spiders cannot feed for a while.

Newly shed 8mm male Mediterranean False Widow, Steatoda paykulliana. Photographed 10th December 2023. (Accidental import specimen 5).

8mm male Mediterranean False Widow, Steatoda paykulliana. Photographed 13th December 2023. (Accidental import specimen 5

Three days after shedding its skin this male darkened considerably and took on the beautiful adult colours. It now looked very different to how it looked immediately after shedding.

8mm male Mediterranean False Widow, Steatoda paykulliana. Photographed 13th December 2023. (Accidental import specimen 5

Tiny 3mm juvenile Mediterranean False Widow, Steatoda cf paykulliana. Photographed 12th October 2023. (Accidental import specimen 6).

On 11th October 2023 Rachel Hemers found a tiny 3mm Steatoda species in her fruit bowl, after buying imported pomegranates from her local greengrocer in Otley, West Yorkshire.

Pomegranates are imported to the UK from several countries in the Mediterranean, including Greece, Turkey and Cyprus. The majority of imported pomegranates that come into the UK from the Mediterranean originate from Spain, and the greengrocer has since confirmed that these particular pomegranates were imported from Spain.

The spider has been hesitantly identified as a young juvenile Steatoda paykulliana. Without knowing for sure that the spider arrived with the pomegranates, and therefore without being 100% certain of its country of origin, it's impossible to identify this Steatoda specimen with absolute certainty as Steatoda paykulliana yet though. There is always the possibility that this spiderling may well be a different Steatoda species that I've not previously encountered. It would be exciting if that turns out to be the case. Unfortunately there's very little online information available on most of the Steatoda species found elsewhere in the world. Until this spiderling reaches maturity we'll have to wait and see if it turns out to be anything other than Steatoda paykulliana.

* Grateful thanks to Rachel for sending this spider to me to be raised in captivity. *

Original Facebook post in British Spider ID Group

Tiny 3mm juvenile Mediterranean False Widow, Steatoda cf paykulliana. Photographed 12th October 2023. (Accidental import specimen 6).

6mm sub-adult Mediterranean False Widow, Steatoda paykulliana. Photographed 10th December 2023. (Accidental import specimen 6).

6mm sub-adult Mediterranean False Widow, Steatoda paykulliana. Photographed 13th December 2023. (Accidental import specimen 6).

6mm sub-adult female Mediterranean False Widow, Steatoda paykulliana. Photographed 13th December 2023. (Accidental import specimen 6).

9mm sub-adult female Mediterranean False Widow, Steatoda paykulliana, Captive-bred specimen CB3-4-10.

Steatoda paykulliana Breeding attempt 3.

Pairing the adult male, Accidental import specimen 5, with the sub-adult female, Accidental import specimen 6.

On 15th January 2024 the adult male, Accidental import specimen 5, was introduced to the sub-adult female, Accidental import specimen 6. The male kept his distance for the first 6 days but within a week the two spiders were coupled together and sharing a web. The male continued feeding whilst the two were partnered together but as with my previous pairing attempts the female stopped feeding once the male was accepted into her web. Adult male Steatoda paykulliana do not live long once they reached maturity and I was hoping that this male specimen would last long enough to see this sub-adult female reach maturity so copulation could take place.

Unfortunately on 4th March 2024 the adult male, Accidental import specimen 5, was found dead at the edge of the web. The spider was not wrapped in silk so it's clear the female specimen played no part in his demise. The male had lasted around 11 weeks since reaching maturity, and was probably only around 9 months old, but definitely less than a year old, when it died. This was particularly disappointing as the male was feeding on a cricket the evening before it died and appeared healthy and active.

Steatoda paykulliana Breeding attempt 4.

Pairing the adult male, Captive-bred specimen 3-4-16, with the female, Accidental import specimen 6.

On 1st April 2024 the female Steatoda paykulliana, Accidental import specimen 6, still looked immature. She was still only 8mm in body-length and still had yellow abdominal markings. It had been three months since I last introduced a male to her enclosure. At this stage I decided to introduce one of my captive bred males that had recently reached maturity. The adult male, Captive-bred specimen 3-4-16, was 7 months of age when he reached maturity. This male was 8-9mm in length at this age, so larger than the female, and I didn't worry too much that she would try to eat the male when introduced. I introduced the male into the enclosure of the female, Accidental import specimen 6, whilst he was still in his pot. The lid of his pot was removed so the male was free to leave his pot and explore her enclosure if he wished to. The male quickly exited his pot and entered the female's web. Initially the female moved away to the outer edge of her web, but within an hour she had moved back into her retreat at the base of the web. Over the next two weeks the two spiders were often seen in fairly close proximity. The male didn't have much of an appetite but would feed occasionally. The female stopped eating completely since the male was introduced into her enclosure.

On the 16/04/2024, at 8:30pm, I witnessed what I believed was mating between the male CB3-4-16 and the female Accidental import specimen AI6. This surprised me as I wasn't aware that the female had reached maturity at this stage. She was still fairly small at just 8mm in body-length. She also still had very yellow abdominal markings, typical of a sub-adult female specimen. Mating was initiated by the male approaching the female from above in their web. The female turned to face the male and he began to perform a dance, with rhythmic strumming of his front legs. The female then lunged aggressively at the male. The male drew back slightly and then once again performed his dance as he moved closer to the female. This cycle was repeated three times before the male moved beneath the female. The female lifted her legs out of the way and the male could be observed to stretch forward his pedipalps and place them in the region of the female’s epigyne. This was also performed three times. The entire mating process lasted just a few minutes. Immediately after the third time the female then grabbed at the larger male as she would her prey. The male immediately fled and ran away from the centre of the web, and the female pursued him. Once she had chased him to the outer edges of her web she then returned back to the centre of the web. On two further occasions that evening the male tried to re-enter the web but was chased away by the female. The female, who hadn’t eaten for several weeks, then caught hold of a dead cricket, which had been in the web for 3 days, and carried it back into her retreat, where she began feeding on it. Her appetite had returned as soon as mating had taken place, and the male’s pheromones no longer seemed to suppressed her appetite. I was surprised the next morning to see both male and female specimens both back in the retreat of the web, with no disharmony between them. During the previous evening's show of aggression from the female the larger male exhibited no defensive behaviour towards the female at all. It was after all in his interests that the female, who was probably now carrying his sperm inside her, should survive unharmed.

On 23/04/2024 the male and female were still sharing the web in close proximity. The male was observed to wrap a dead cricket, that had been left in the web for several days. Once wrapped the male carried the wrapped carcass of the cricket and presented it to the female. The female then appeared to feed on the dead cricket. The giving of nuptial gifts is a practice that is often observed with other species, including the Nursery-web Spider, Pisaura mirabilis, that is native to the UK. With the South American Long-legged Water Spider, Paratrechalea ornata, the male usually wraps prey items and presents them to potential female mating partners to ensure the male's advances are accepted. Studies have revealed that on at least 20% of occasions these wrapped nuptial gifts do not contain a prey specimen at all, but instead contain nothing more than worthless leftovers, which are heavily wrapped and presented to the female. Both offerings seem to be equally effective in gaining favour with the females. - LINK

Steatoda paykulliana Breeding attempt 5.

Pairing the adult male, Captive-bred specimen 3-4-7, with the proven adult female, Accidental import specimen AI4.

On 10th April 2024 I introduced the adult male Steatoda paykulliana, Captive-bred specimen 3-4-7, into the enclosure of the proven adult female, Accidental import specimen AI4.

The adult female had run out of male sperm since she was paired with the last male back on . I decided to see if she would mate with another male, and then go on to produce more viable egg-sacs. As soon as the male was introduced he immediately pursued the female, who was much larger than he was. The female ran away from the male every time he got close to her. The male continued to chase after her and eventually the female decided that she'd had enough of his advances. The female then turned the underside of her abdomen towards him and positioned herself to start throwing strands of silk, exactly as she would if she were about to wrap up her prey. The male sensed the danger and immediately halted his tracks. He remained at the far side of her web where it was safe. After several hours the male then began to try a slower approach. The male began communicating with the female by repeatedly plucking at the web. He could also be clearly seen to stridulate by stroking his jerking abdomen with his legs. By the next day the female seemed to have accepted him in her web and the two spiders were then regularly seen in fairly close proximity to each other. Mating was not observed though.

Steatoda paykulliana Breeding attempt 6.

Pairing the adult male, Captive-bred specimen 3-4-9, with the sub-adult female, Captive-bred specimen 3-4-6

On 10th April 2024 I introduced the adult male Steatoda paykulliana, Captive-bred specimen 3-4-9, into the enclosure of the sub-adult female, Captive-bred specimen 3-4-6.

Both of these captive-bred specimens were around 7 and a half months of age. This male was 8-9mm in length at this age, and slightly larger than the female, and I didn't worry too much that she would try to eat the male when introduced. I introduced the male into the enclosure of the female whilst he was still in his pot. The lid of his pot was removed so the male was free to leave his pot and explore her enclosure if he wished to. The male took 24 hours to exit his pot and enter the web of the sub-adult female. The female immediately accepted him in her web and the two spiders were often with close proximity of each other. As females take far longer to reach maturity I did not expect this to be a successful pairing, and fully expected the male to die of old age before the female reached maturity and would be able to breed.

Steatoda paykulliana Breeding attempt 7.

Pairing the adult male, Captive-bred specimen 3-4-18, with the sub-adult female, Captive-bred specimen 3-4-10

On 16/04/2024 I introduced the adult male Steatoda paykulliana, CB3-4-18, into enclosure of sub-adult female, CB3-4-10. The lid of his pot was removed so the male was free to leave his pot and explore her enclosure if he wished to. The male took 12 hours to exit his pot and enter the web of the sub-adult female. The female immediately accepted him in her web and the two spiders were often with close proximity of each other. With both male and female specimens being exactly the same age I had little hope that this pairing would be successful. I expected, as I had seen before with previous pairings, that the male would eventually sadly die long before his female partner even reached maturity.

Steatoda paykulliana Breeding attempt 8.

Pairing a captive-bred adult male with a captive-bred sub-adult female.

Three of my captive-bred Steatoda paykulliana, which were the offspring of the successful breeding of the accidental imports 3 and 4, were sold to Lisa Jenkins.

On 23/04/2024 Lisa introduced an adult male Steatoda paykulliana into enclosure of what we believed was a sub-adult female. The male immediately performed multiple dances for the female and was immediately accepted by her. Within an hour successful breeding was clearly observed between the two spiders. It is possible that the female had matured earlier than expected. It is also possible that the female still had one more moult to go before officially reaching maturity. Until the final moult the epigyne of the female is covered by a layer of skin. Once the final moult has taken place the epigyne is fully exposed and accessible to male suitors. Sometimes the epigyne can be fully developed before the female has had her final moult. On occasion the male may detect this and may tear away the layer of skin that covers the epigyne and proceed to mate with a technically immature specimen.

On 24/04/2024 the male and female were still sharing the web in close proximity. The male was observed to wrap a dead fly that had been laying at the bottom of the enclosure for several days. Once wrapped the male carried the wrapped carcass of the dead fly and deposited it in the silken retreat where the female was at rest. The giving of nuptial gifts is a practice that is often observed with other species, including the Nursery-web Spider, Pisaura mirabilis, that is native to the UK. With the South American Long-legged Water Spider, Paratrechalea ornata, the male usually wraps prey items and presents them to potential female mating partners to ensure the male's advances are accepted. Studies have revealed that on at least 20% of occasions these wrapped nuptial gifts do not contain a prey specimen at all, but instead contain nothing more than worthless leftovers, which are heavily wrapped and presented to the female. Both offerings seem to be equally effective in gaining favour with the females. - LINK

Steatoda cingulata, a similar species to Steatoda paykulliana.

There is another non-native Steatoda species, which although never found in the UK, can sometimes be mistaken for Steatoda paykulliana. The two species usually come from completely different parts of the world, but there are countries such as India where both Steatoda paykulliana and Steatoda cingulata do occur. As an adult Steatoda cingulata can look very similar to Steatoda paykulliana. Adult Steatoda cingulata are black, or very dark brown in colour, and usually exhibit a yellow or white lateral band at the front of the abdomen, just like adult female Steatoda paykulliana. What distinguishes adult Steatoda cingulata from Steatoda paykulliana are the legs. The legs of mature female Steatoda paykulliana are almost completely black. All the legs of mature male Steatoda paykulliana usually still retain the wide, bold, orange and black bands, as seen on juvenile specimens. Mature female Steatoda cingulata have black front legs, but often just the rear legs still exhibit the orange and black bands. Occasionally very feint bands can still be seen on the front legs but these are hardly visible compared to the bands on the rear legs. As with mature male Steatoda paykulliana the legs of mature male Steatoda cingulata usually still retain the orange and black bands on all their legs, as also seen on juvenile specimens. Sometimes these bands can be very feint though. Both male and female Steatoda cingulata exhibit one or two promarginal teeth on the chelicerae, which distinguishes them from any Latrodectus species. Steatoda cingulata can often be found under large stones, and prefers open dry areas, stony of sandy fields, with sparse, low vegetation. The tangled webs are built close to the ground and the egg-sacs are white or very pale pink. This species has been observed feeding on grasshoppers, moths, beetles and ants, that approached the web.

Steatoda cingulata is found in southern and north-east Asian countries, including the Philippines, India, Laos, China, Korea, Japan, Taiwan, Malaysia, Sumatra, Indonesia, Java and Vietnam. Steatoda cingulata has never been found in the UK. In their native countries this species can go by various common names, including: Moon-spotted Screech Spider, Half-moon Fat-Bellied spider, Belted Fat-Bellied Spider, White-Margined Spider. LINK LINK 2

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Despite the visual resemblance of Steatoda paykulliana to the more venomous Latrodectus species most Latrodectus species do not possess the red lateral band at the front of the abdomen, as seen on Steatoda paykulliana. There are exceptions to this though, Latrodectus menavodi, the Madagascan Black Widow is one such exception. Latrodectus menavodi usually looks quite different to Steatoda paykulliana, and is easily distinguished by the 9 or 10 white spots on the top of the abdomen, and a small red line or spot on the rear of the abdomen. Latrodectus menavodi also displays a red lateral band at the front of its abdomen too though, similar to that of Steatoda paykulliana. On some mature female Latrodectus menavodi specimens the majority of the abdominal markings can fade, or even completely disappear, leaving just the red lateral band, and looking quite similar to Steatoda paykulliana. A close look at this red abdominal band on Latrodectus menavodi reveals a distinct difference though. On Steatoda paykulliana the red lateral abdominal band is usually continuous, but on Latrodectus menavodi the red lateral abdominal band is broken and has a gap in the centre.

There are of course other subtle differences to help distinguish between the two species, including the proportionally longer legs of the Latrodectus species and the slightly different eye arrangements.

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Variations in the abdominal markings of Steatoda species

The abdominal markings on Steatoda species can show great variation from one specimen to the next. The markings can also change considerably during the lifecycle of each spider. Older specimens often exhibit duller and simpler markings, if any are still present at all. The diagrams below depict many of the variations found within the Steatoda genus. The abdominal markings seen on some specimens are not always conclusive and some specimens can easily be confused with other Steatoda species. When the abdominal markings don't clearly indicate which species is present then one has to look at other key identifying features such as: the body-length, the leg length, colour and annulations, the habitat and location of web. and the side view of lateral band on the abdomen.

Variations in the abdominal markings of Steatoda paykulliana

Variations in the abdominal markings of Steatoda triangulosa

Variations in the abdominal markings of Steatoda bipunctata

Variations in the abdominal markings of Steatoda nobilis

Variations in the abdominal markings of Steatoda grossa

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4.5mm adult female Triangulate Cobweb Spider (Steatoda triangulosa)

Triangulate Cobweb Spider / Triangulate Comb-footed Spider - (Steatoda triangulosa)

The Triangulate Cobweb Spider is a small and rare species of False Widow Spider, found occasionally in England. In the UK most records are from specimens found around houses, or garden centres, and its webs are usually made low to the dirt to catch crawling insects, particularly ants, woodlice and ticks. It's also not uncommon for these spiders to make their webs around window frames of human habitations, to catch flying insects. In European countries, where Steatoda triangulosa is considered to be native, this species is found indoors on more than 75% of sightings.

Females grow to a body-length of around 4-5mm and the slightly smaller males 3.5-4mm. It is not clear whether Steatoda triangulosa is a very rare, but fully native, species to the UK, an established non-native or an accidental and occasional import, although the latter is most likely. The Triangulate Cobweb Spider has very distinct zig-zag markings on its abdomen which make it easy to identify. In western Europe and North America, where this species is common, it is known to prey on small spiders considered dangerous to man, including the Recluse Spider. There are no records of the Triangulate Cobweb Spider ever biting humans though, and the venom of this spider is not considered as significant to humans either. One of the few records of Steatoda triangulosa being found in the wild here in the UK came from 11th July 2018 when a sub-adult specimen was found in a shed in Lincolnshire. LINK Another record came from Brighton on 21st April 2018, when a specimen was found in a garden under a tarpaulin. LINK

* I would like to give huge thanks to Gen Popovici for sending me this specimen to photograph and add to my website. *

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4.5mm adult female Triangulate Cobweb Spider (Steatoda triangulosa)

Both of the non-native False-Widow spiders, Steatoda paykulliana and Steatoda triangulosa are found occasionally in the UK. Steatoda paykulliana usually turn up amidst imported fruit, whilst the much smaller Steatoda triangulosa seem to turn up at garden centres, presumably arriving in the UK amidst imported plants.

Some specimens of Steatoda paykulliana, particularly sub-adults and males, can exhibit abdominal markings slightly similar to those found on Steatoda triangulosa. Using photos of both species I have created this image showing the difference in typical abdominal markings between the two species. Both species can have brown annulated legs as a sub-adult. As they mature the differences are very obvious and Steatoda paykulliana take on a much darker, usually very dark black appearance. The abdominal markings on Steatoda paykulliana fade as the spider ages but those markings that are retained can vary in colour from white, orange, yellow or red. Steatoda triangulosa always retain their brown and cream colours and their triangulate abdominal markings as an adult. Only a minority of older female Steatoda paykulliana retain their upper abdominal markings and the majority of specimens lose most markings apart from the red band at the front edge of their abdomen. Male Steatoda paykulliana usually retain both their leg annulations and their abdominal markings though.

Distinguishing between Latrodectus and Steatoda species.

Eye arrangements of Latrodectus and Steatoda species.

Sometimes it can be very difficult to distinguish between a dark, unmarked Steatoda specimen and a Latrodectus specimen. The two can be reliably separated by taking a close look at the eye arrangements. Spiders of both Steatoda and Latrodectus genus have eight eyes, and the arrangements of both are very similar. However, there is a distinctive difference when we look at the outside pairs of eyes, the posterior lateral eyes and the anterior lateral eyes. On Latrodectus species there is an obvious gap between the PL eyes and the AL eyes. However, when we look at the eyes of all Steatoda species we find that the PL eyes are touching, or very nearly touching, the AL eyes. In many cases the PL eyes are actually fused together with the AL eyes.

The abdomen is one helpful indicator that may help to distinguish between the two genus without getting too close to the spiders. Generally Latrodectus species have a taller, narrower, and more teardrop-shaped abdomen than that of Steatoda species. The legs are another helpful indicator when trying to identify the genus from a photo. Latrodectus species typically have proportionally longer legs when compared to those of Latrodectus species.

There is also another way to distinguish between Steatoda sp. and Latrodectus sp. but it requires microscopic examination of the chelicerae. The chelicerae of Steatoda sp. usually have one or two tiny teeth near the base of the fangs. Many Steatoda species exhibit one tooth on the male and two smaller teeth on the female. Latrodectus species do not possess these cheliceral teeth.

When researching this information in March 2023 there were plenty of sources that seem to contradict this information regarding Steatoda nobilis though. Some sources claim that both male and female Steatoda nobilis have no cheliceral teeth, whilst other sources claim that both sexes of Steatoda nobilis have one cheliceral tooth. Even experienced arachnologists couldn't agree on this matter. Hopefully future microscopic study of the chelicerae of Steatoda nobilis specimens will confirm the reliability of using this method to distinguish Steatoda nobilis from Latrodectus sp.

Eye arrangements of Latrodectus geometricus and Steatoda paykulliana.

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White-Spotted False Widow Spider - (Steatoda albomaculata)

A rare and locally distributed, small species of False Widow Spider. Steatoda albomaculata is confined to central-southern England and East Anglia, where it is widespread on heathland sites in Dorset, the New Forest, Surrey and Breckland. It's typical habitat is dry, sandy, heathland, shingle or under stones. Norfolk seems to be an area where this species has a stronghold at several coastal sites. - LINK

The White-Spotted False Widow spins its minimal web in very low vegetation, often between large stones. Webs are often built amongst leaf litter and detritus, in small depressions on bare sandy soil. The spider's retreat is often beneath the web, in a small hole in the ground. - LINK LINK 2

This species is often found in areas that support large numbers of ants, upon which this spider readily preys. They have also been observed wrapping beetles at ground level in silky threads. Females grow to around 3-6mm and males 4-5mm. Adults are usually found from April to October, with two peaks from May to June, and from August to September. This species has declined significantly in recent years. This could be partly due to habitat loss. The White-Spotted False Widow is dependant on bare sandy soil and the improved control of heathland fires in recent years could be detrimental to the long-term survival of this spider.

In southern Europe there is another Steatoda species that's rarer and very difficult to separate from Steatoda albomaculata, and that is Steatoda incomposita. Some sources claim that the two can be distinguished if you have a clear view of the ventral side. Steatoda incomposita has three white lines of the underside of the abdomen, which usually converge to form an anchor pattern, whereas albomaculata has just the one white line. Sub-adult Pachygnatha degeeri can sometimes be mistaken for Steatoda albomaculata. - LINK

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Heath False Widow Spider - (Steatoda / Asagena phalerata)

Since being reclassified from the Steatoda genus to the Asagena genus in 2019 there could be some debate as to whether this Tangle Web Spider should still be regarded as a False Widow Spider or not. This uncommon, but widespread, species is small in size with a maximum body-length of 3-5mm for females, and 4-4.5mm for males. It is usually found at ground level, in dry sunny places, with little vegetation and sand dunes. It is most commonly found in the vicinity of ants, which form most of its diet. The Heath False Widow rarely uses any silk to catch and subdue its typical ant-prey, suggesting that its venom is highly effective and fast acting on ants. It can often be found at ground level hunting around ants nests. Because most Asagena phalerata are encountered actively hunting on open ground for ants it is sometimes reported that this Theridiidae species does not make a web. Adult females definitely do make webs though. Whether this is true of adult males is uncertain. The webs are built at ground level, typically with a retreat in a small hole in the soil. Tylan Berry has documented this - LINK.

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Black Widows and Button Spiders in the UK - Latrodectus species

There are no species of Black Widow, Button Spider or other Latrodectus species, established anywhere in the UK. However, Latrodectus species have occasionally been known to arrive in the UK as accidental stowaways amidst imported goods. My research has lead me to find a number records of Latrodectus species arriving in the UK. Although the number of official records is very low I suspect the true number of Latrodectus species reaching the UK, hidden amidst imported goods, may be much higher. With the majority of such finds being made on commercial premises it is highly likely that most of these sightings are not recorded or reported. The Brown Widow, Latrodectus geometricus, arrives here on very rare occasions hidden in imported fruit. Brown Widows arriving in the UK usually do so hidden amidst imported grapes, and are nearly always dead on arrival though. It's unclear whether they succumb to the cold refrigerated temperatures during transportation or whether they die from the pesticides that are used to treat the fruit. Western Black Widows, Latrodectus hesperus, arrive here on very rare occasions, hidden in imported cars from the USA. And the Red-back Spider, Latrodectus hasselti, has occasionally been imported along with heavy machinery. In the UK no Latrodectus species have ever become fully established here in the wild though, largely due to our damp climate.

There are wild and unsubstantiated rumours and reports of previous introductions of Latrodectus species in the UK, whether intentionally or by accident. However, there is little or no evidence to support claims of most of these apparent introductions. Even if there was any truth to any of these rumoured introductions then the spiders certainly died out and failed to successfully establish viable, long-term breeding colonies in the UK, as there are currently no wild Latrodectus colonies in the UK today.

In August 2023 Chris Newman, the director of the National Centre for Reptile Welfare, informed me of two previous colonies of Latrodectus species in the UK that he had personal dealings with. The first was the Western Black Widow, Latrodectus hesperus, which became established around a warehouse close to Heathrow Airport, that was the site of a large importer of fresh produce from California. The second site was at an undisclosed military base, where the Redback Spider, Latrodectus hasselti became established for a number of years. On both occasions these Latrodectus specimens were only established in synanthropic environments.

Chris Newman has been working with Latrodectus species in produce since 1988. During this time Chris worked for a number of importers / distributors, principally looking at Latrodectus hesperus. In Chris's opinion "Latrodectus hesperus is a species that could become established in the UK in localised areas, warehousing etc., but it is unlikely to become invasive as its intolerant of our damp winters." Chris went on to say "Latrodectus hasselti is another kettle of fish, so to speak. It has become established in Japan in areas with winters not dissimilar to ours. This is a species that I personally think could become established in the UK, I’m not so sure about Latrodectus geometricus, I think it would be too temperature sensitive".

It's interesting that Chris believes Latrodectus hasselti should be regarded as the greatest Latrodectus threat to the UK though. Research that I read, published in October 2022, concluded the following though:

"Thus, despite the fact that human transport may regularly introduce L. hasselti spiders to new areas, our model suggests that the likelihood of establishment and spread will heavily depend on local humidity and temperature."

In Australia, where Latrodectus hasselti are native, it is believed they are being displaced in some coastal areas by Latrodectus geometricus. Observations there have shown that Latrodectus geometricus does have a preference for cooler areas when compared to Latrodectus hasselti though. Due to its sudden expansion in range in recent years many countries now consider Latrodectus geometricus to be highly invasive. As with Steatoda nobilis it's unclear why Latrodectus geometricus has suddenly expanded its range so dramatically in the last 10-20 years. - LINK

Venom - by Steve Backshall, 2007

One source of unsubstantiated claims comes from the 2007 book "Venom", written by BBC presenter, Steve Backshall. On page 39 the book claims:

"There are definitely members of the Latrodectus genus doing very well in small pockets around Britain. The question is whether they are relict populations of an indigenous arachnid, or more recent imports. If the latter, have they arrived here under their own steam or by hitchhiking with humans? Certainly the proliferation of black widows around the caravan site of an arachnid breeder in Kent is due entirely to tiny spiderlings ballooning once they have left the egg-case. This is the process many spiderlings use to travel away from their siblings - they will climb up to a suitably high vantage point and eject a stream of silk, which then gets caught in the wind, carrying the enterprising Phileas Fogg-esque juvenile off into the air. Spiderlings can travel immense distances this way - potentially across the Atlantic, and certainly across the English Channel."

When I researched these claims this book was unfortunately discredited as inaccurate by expert arachnologist, Martin Bell, who makes specific reference to total inaccuracies on the book's information on Phoneutria venom. Although I'm a fan of Steve Backshall the book lists no references to substantiate its claims of Latrodectus colonies being found in the UK, and therefore cannot be regarded as reliable unfortunately. The book also supposedly shows a photo of "Latrodectus lilianae" to accompany this section, which is actually a photo of an adult female Latrodectus tredecimguttatus.

Black Widows, Latrodectus species.

There are no spiders more infamous than the highly venomous Black Widow Spiders. As of 2023 the Latrodectus genus of True Widow Spiders currently contains 35 different species, that can be found in warmer countries across the world. This includes the two recently described species from 2021, Latrodectus garbae and Latrodectus hurtadoi, from Colombia, and the 2019 discovery, Latrodectus umbukwane, from South Africa. (See full list here, or on this website - Black Widow Species list)

But are the Black Widows really as deadly as their reputation suggests? Although Latrodectus species do have a medically significant bite there are very few human fatalities as a result. Not all Latrodectus species are equally dangerous though. Latrodectus mactans, which is commonly referred to as the Southern Black Widow, is a common species found in the southern states of the USA. Although bites from this species are both painful and extremely unpleasant, no one has actually died as a result of a bite from a Southern Black Widow. YouTuber "Jack's World of Wildlife" filmed himself taking a severe envenomation from this species which can be watched here: LINK.

Although the Black Widow has a reputation of being deadly to humans there have been no confirmed deaths recorded as a result of bites from any of the 5 species of Latrodectus spider found in the USA for many years. From the year 2000 up until the year 2008 there were an incredible 23,409 records of bites to humans from Latrodectus spiders in the USA, and yet not a single one of these bites resulted in a human fatality. LINK

The toxicity of the venom of Latrodectus species varies from one species to the next, and even from one specimen to the next, depending on a variety of factors including geographic location.. These are the typical LD50 values for Latrodectus species found in Northern USA:

Brown Widow, Latrodectus geometricus = .43 mg/kg (in Florida) & .223 mg/kg (in Venezuela) LINK

Western Black Widow, Latrodectus hesperus = .84 mg/kg (IV) LINK / 0.64 mg/kg LINK

Southern Black Widow, Latrodectus mactans = 1.39 mg/kg (IV) & .90 mg/kg (SC) LINK / 0.26 mg/kg LINK

Red Widow, Latrodectus bishopi = 2.2 mg/kg (could be IP) LINK

Northern Black Widow, Latrodectus variolus = 1.8 mg/kg (IP) LINK / 1.20–2.70 mg/kg LINK

These can be compared with the Mediterranean Black Widow, Latrodectus tredecimguttatus = 0.59 mg/kg LINK

It's important to remember that no species of Black Widow, or other Latrodectus species, are established anywhere in the UK.

The UK Government once debated the risk of the Black Widow Spider becoming established in the UK, as far back as 1927. These spiders were deemed at that time to be of no risk to the UK - LINK Very occasionally though juvenile specimens or egg-sacs do turn up in the UK, usually amidst imported fruit. Adult specimens of Latrodectus species also turned up on occasions, as accidental imports hidden amidst other imported goods, particularly cars. The three species of Black Widow found in the USA, where most imported cars carrying accidentally imported Latrodectus species are imported from, include the Western Black Widows, Latrodectus hesperus, the Southern Black Widow, Latrodectus mactans, and the Northern Black Widow, Latrodectus variolus, are not regarded as invasive species and do not adapt well to climatic variations. It is unlikely that any of these would successfully establish breeding colonies in the UK's damp climate. In fact Black Widows in some countries are reported to be on the decline due to the invasive and highly adaptable Brown Widow, Latrodectus geometricus, which is expanding its range in many parts of the world. I would expect Steatoda nobilis to easily outcompete any Black Widows if they were to establish a colony anywhere in the UK. My research has lead me to find the following examples of Latrodectus species that have been discovered in the UK:

Recent records of Latrodectus species found in the UK

1) On 12/01/2020 a Brown Widow, Latrodectus geometricus, with its egg-sac, was found in in Cwmbran, Wales, amidst imported black grapes bought from Asda, and originating from Brazil. LINK LINK 2 LINK 3

2) On 15/03/2016 three egg-sacs of the Brown Widow, Latrodectus geometricus, were found amidst imported red grapes in Wokingham, Berkshire. LINK

3) A Juvenile Mediterranean Black Widow, Latrodectus tredecimguttatus, was found amidst imported red grapes from Egypt, bought at Sainsburys, July 15th 2021 LINK

4) On 20th November 2021 A pest controller was called to deal with 11 specimens of both male and female Western Black Widow Spiders, Latrodectus heperus, found amidst wooden pallets on a shipping container in Rochdale. The shipment had come from California, where they have both Southern and Western Black Widows. However the feint lighter banding on the legs of these spiders identified them as Western Black Widow Spiders, Latrodectus heperus rather than the Southern Black Widow Spiders, Latrodectus mactans. LINK

5) On 3/06/2015 an adult female Black Widow Spider and her spiderlings were found in a punnet of white grapes imported from Mexico, and bought from Asda in Leamington Spa, Warwickshire. LINK

6) In March 2022 an adult female Latrodectus sp. was found in a warehouse in Billericay, Essex, that imports cars from northern USA. Unfortunately the spider was destroyed before it could be accurately identified or rehomed. LINK In the USA, where it's believed this spider originated from, there are 5 species of Latrodectus spider that can be found in various different states. These include:

Latrodectus Geometricus, the Brown Widow

Latrodectus heperus, the Western Black Widow

Latrodectus variolus, the Northern Black Widow

Latrodectus mactans, the Southern Black Widow

Latrodectus bishopi, the Red Widow

Only two of these Latrodectus species have the feint lighter banding on the legs, as seen on the specimen found at Billericay, so the spider's identity could be narrowed down to one of these two species. One is Latrodectus Geometricus, the Brown Widow, and the other is the Western Black Widow, Latrodectus heperus.

7) On 20th March 2022 an adult female Brown Widow, Latrodectus geometricus, was found amidst red grapes, bought from Tesco in Bellshill, North Lanarkshire, in Scotland, and imported from South Africa. Unfortunately the spider was dead on arrival. LINK

8) On 15/05/2021 a dead adult female Brown Widow & her egg-sacs were found in Newark, Nottinghamshire, amongst Red Grapes, imported from South Africa, and purchased from Morrisons. LINK

9) On 08/04/2021 a black spider ,with a red dot on its abdomen, was found in a garden in Buckinghamshire. It was not possible to tell for sure if it was a female Steatoda paykulliana or a Latrodectus species. LINK

10) On 21/07/2022 an adult female Brown Widow was found on the outside of a shipping container at Southampton Docks, in Hampshire. It's believed the container originated from Vietnam. LINK

11) On 22/08/22 two adult female Western Black Widows, Latrodectus hersperus, were found in Southport, Merseyside, living in a car that had recently been imported from Arizona, USA. They were able to survive here due to the long, hot summer of 2022. Latrodectus hersperus is a species typically associated with dry, desert-like conditions in the USA and there is no chance of this species being able to survive the cold, damp climate of the UK throughout much of the year. LINK LINK 2

12) On 13/01/2020 an adult female Brown Widow, Latrodectus Geometricus, & egg-sac were found in Black Grapes, purchased from Asda in Cwmbran, South Wales. The grapes had been imported from Brazil. LINK

13) In August 2015 an adult female Black Widow, either Latrodectus mactans or Latrodectus hesperus, was found living beneath a VW Camper Van in Pershore, Worcestershire. The campervan had recently been taken out of storage following its importation to the UK from California, USA. LINK

14) On 9th March 2022 an adult female Brown Widow, Latrodectus geometricus, was found amidst white grapes bought from Asda in Middleton, Greater Manchester, and imported from South America. Unfortunately the spider was accidentally killed on discovery. I'm very grateful that the dead specimen was sent to me to photograph and identify. See images below. LINK Once photos were taken the dead spider was then forwarded on to Dr John Dunbar, at Venom Systems & Proteomics Lab at The Ryan Institute Zoology, for DNA analysis.

15) On 30th October 2015 an adult female Black Widow was found in Uckfield, East Sussex, on a truck that had recently been imported from Arizona, USA. The spider was taken into captivity. LINK

16) On 25th April 2023 a Latrodectus sp., probably Latrodectus geometricus, was found in red grapes, being sold on a market stall outside Queen Elizabeth Hospital, in Birmingham. The spider was already dead when discovered. LINK

17) On 1th September 2018 - Gloucestershirelive.co.uk reported claims of around 100 Redback Spiders, Latrodectus hasselti, being found on a large piece of electrical equipment in Northway, Tewkesbury, Gloucestershire. The equipment was brought over from New South Wales, in Australia, to be serviced in Britain, when the spiders were discovered and pest control services were called. LINK

18) On 3rd August 2023 a Black Widow spider was found alive in its web in the engine bay of a recently imported Chevrolet pickup truck from California, USA to Banbury, Oxfordshire, in the UK. The spider was easy to identify as the Western Black Widow, Latrodectus hesperus. Latrodectus hesperus is the only Latrodectus species found in California. LINK

On 21st August 2023 Dmitri Logunov, an expert in the field of arachnid identification at the Manchester Museum, was very helpful in providing me with the following three records that the Manchester Museum have of Latrodectus species arriving in the UK with imported goods. All three Latrodectus specimens were formally identified by the museum and now form part of their arachnid collections.

19) On 16th November 2011 a live female Latrodectus geometricus was found in a skip containing cardboard packaging. It arrived in the UK hidden amidst imported Saytex Fire Safety equipment, which had been stored at both Magnolia, Arkansas, and Dallas, Texas, in the USA.

20) On 14th November 2007 a female Latrodectus variolus arrived in West Yorkshire hidden amidst imported grapes from California, USA.

21) During the summer of 2003 an unidentified juvenile female Latrodectus specimen was donated to the museum after it arrived in the UK in a car tyre that had been imported from California, USA.

22) On the 17th June 2011 the BBC reported on an adult female Black Widow spider being found at Chatham Dockyard, in Kent, amidst imported cars. The spider was taken away to a local vet in Maidstone, who passed the spider onto London Zoo. The spider went on to produce an egg-sac. The BBC's article was full of misinformation, such as claiming that male Black Widows are not venomous, which they are. Kent Online reported the story more accurately.

23) On 19th October 2023 at least two adult female Western Black Widows, Latrodectus hesperus, spiderlings and egg-sacs, were found in North Wales on an imported car from Arizona, California, USA. The car came with paperwork to prove it had been fumigated with pesticide gas before being transported, The owner of the car had been driving the car for two months in the UK, and it was only when the car was being worked on that the spiders were discovered. - LINK LINK 2

24) On 4th December 2023 a 10mm dead adult female Brown Widow, Latrodectus geometricus, was found in a fruit bowl. Closer inspection revealed webbing on the white grapes that had been bought from the Hersham branch of Lidl's, in Surrey. The grapes were imported from Peru. - LINK

25) On 9th December 2023 a dead adult female Brown Widow, Latrodectus geometricus, was found with webbing amidst red grapes purchased from Sainsbury's in Broadstairs, Kent, that were imported from Peru. - LINK

26) On 5th January 2024 a dead adult female Brown Widow, Latrodectus geometricus, was found amidst imported white grapes from Peru. The grapes were purchased from a Co-op store in Stockport, Greater Manchester. - LINK

27) On 7th January 2024 a dead adult female Brown Widow, Latrodectus geometricus, was found amidst imported red grapes from Brazil. The grapes were purchased from a Lidl store in Bournemouth, Dorset. - LINK

28) On 23rd January 2024 a dead adult female Brown Widow, Latrodectus geometricus, was found in white grapes imported from South Africa. The grapes were purchased in Bolton, Lancashire. - LINK

29) On the 24th January 2024 a dead adult female Brown Widow, Latrodectus geometricus, was found in red grapes purchased from Asda in Duffryn, Newport, South Wales. - LINK

30) On the 25th January 2024 a dead adult female Brown Widow, Latrodectus geometricus, was found in imported red & green mixed grapes delivered from Shrewsbury. - LINK

Deceased 9mm adult female Brown Widow, Latrodectus geometricus, found amidst white grapes imported from South America, 9th March 2022

* I'd like to give grateful thanks to Elaine Cameron for kindly sending this dead specimen to me so it could be photographed and have its identity confirmed. *

Deceased 10mm adult female Brown Widow, Latrodectus geometricus, accidentally imported with white grapes from Peru, South America, 4th December 2023

* I'd like to give grateful thanks to Brenox Mac Cionnaith, and his sister, for kindly sending this dead specimen to me so it could be photographed and have its identity confirmed. *

Deceased 10mm adult female Brown Widow, Latrodectus geometricus, accidentally imported with white grapes from Peru, South America, 4th December 2023

This close up image of the adult female Latrodectus geometricus shows orange hourglass marking, indicative of Latrodectus geometricus, rather than the ruby red hourglass marking found on many other Latrodectus species. The hourglass marking of Latrodectus geometricus, can very occasionally also be found in red, yellow or even grey though.

Deceased 10mm adult female Brown Widow, Latrodectus geometricus, accidentally imported with white grapes from Peru, South America, 4th December 2023

This close up image of the adult female Latrodectus geometricus shows the eye-arrangement and the key spacing of the outer pairs of eyes that identify the spider as Latrodectus species rather than Steatoda species.

7mm spiky egg-sacs belonging to the Brown Widow Spider, Latrodectus geometricus, found amidst imported grapes from Brazil, 7th November 2021.

31) On the 7th November 2021 Sarah Burgin, from Crewe, Cheshire, found four spiky egg-sacs hidden amidst her Brazilian black grapes, purchased locally. The spiky egg-sacs are distinctive and can only belong to the Brown Widow, Latrodectus geometricus, a species commonly found in Brazil, where the grapes originated from. Latrodectus elegans also produce spiky egg-sacs, but Latrodectus elegans are an Asian species not found on the South American continent. Three species of spider from the Latrodectus genus are reported as occurring in Brazil: Latrodectus mactans, the Southern Black Widow, Latrodectus curacaviensis, the Brazilian Black Widow, and Latrodectus geometricus, the Brown Widow. However neither of the other two species create spiky egg-sacs. LINK . Fertile eggs of the Brown Widow usually take 14-21 days to hatch, but the spiderlings can remain hidden away within the egg-sac from just a few days to another month after hatching. When found it was uncertain whether these egg-sacs would prove to be fertile or not, and if fertile would they have survived the refrigerated transportation process used when exporting grapes? It is common for the Brown Widow to create several egg-sacs at a time, some times with as few as just one or more of those actually containing fertile spider eggs.

7mm spiky egg-sacs belonging to the Brown Widow Spider, Latrodectus geometricus, found amidst imported grapes from Brazil, 7th November 2021.

Brown Widow egg-sacs, 1 - empty, 2 - undeveloped eggs, 3 - dead spiderlings.

Unfortunately the Brown Widow egg-sacs, found amidst imported grapes from Brazil, did not hatch. Eventually the decision was made to investigate why and the egg-sacs were cut open to see if they were fertile or not. Egg-sac 1 was empty and therefore infertile. Egg-sac 2 was full of undeveloped and unhatched eggs. Egg-sac 3 was full of tiny spiderlings that had died. It's clear that two of the egg-sacs would have produced Brown Widow spiders but unfortunately both the eggs and spiderlings had failed to survive, either because of the refrigerated transportation process used when the grapes were exported, or perhaps the grapes were treated with pesticides that had killed the developing spiderlings and eggs.

Brown Widow / Geometric Button Spider / Brown Button Spider (Latrodectus geometricus)

The Brown Widow was originally discovered in South America, although many sources claim that the species originated from southern Africa. The Brown Widow's range now covers many pantropical and subtropical areas around the world. Although this species does turn up in the UK very occasionally, as an accidental stowaway amidst imported fruit and other goods, it is not established anywhere in the UK. The Brown Widow tends to be slightly smaller and usually far lighter in colour than other Black Widow species. Females grow to a body-length of around 7-10mm, whilst the far smaller males only reach 2-4mm. The appearance of the Brown Widow is highly variable but usually ranges from light grey to light brown in colour, with a black & white geometric pattern on the dorsal side of its abdomen, and annulated legs. Darker specimens do sometimes occur though and these can easily be mistaken for juvenile specimens of other Black Widow species, in countries where both species occur, such as the USA. The Brown Widow still possesses the trademark hourglass marking, typical of Latrodectus species, on its underside. However, instead of it being bright red, as with most of its Black Widow cousins, the Brown Widow's hourglass marking is orange, or occasionally yellow.

Bites from the Brown Widow are not usually as serious to humans as other Black Widow species. Although they still possess a potent neurotoxic venom, that effects nerve endings, the yield of that venom is believed to be far lower and the amount of venom injected during a bite is usually considerably less than other Latrodectus species. Most bites from a Brown Widow are not usually medically significant, probably due to the low volume of α-latrotoxin delivered during a bite. The effects are usually confined to the bite area and in 2/3rds of cases result in localised pain, sometimes severe, for 1-2 days and minor swelling for 1-4 days. Sensitivity to venom varies from person to person though and occasionally some bite victims can experience the more severe reactions of Latrodectism usually associated with the more dangerous Black Widow species. One such case in the USA, back in 2008, resulted in a previously healthy, adult male victim needing hospitalisation, experiencing symptoms including severe pain, cramps, nausea & vomiting, and fasciculations in the pectoral and quadriceps muscles. LINK

The expanded distribution of the Brown Widow is, like Steatoda nobilis, believed to be a fairly recent adaptation of the species, and DNA testing of Brown Widow specimens from around the world shows very little variation. The Brown Widow is now classed as an invasive species in many areas and has long been suspected as being responsible for displacing some Black Widow species in their native countries. In a recent study, published in January 2023, it was confirmed that the Brown Widow, Latrodectus geometricus, is definitely displacing Florida’s Southern Black Widow, Latrodectus mactans, and California’s Western Black Widow, Latrodectus Hesperus. The studies revealed that Brown Widows have twice the fertility potential as Southern Black Widows. In experiments comparing development, it was shown that sub-adult Brown Widows grew faster and matured earlier, relative to Southern Black Widows. The Brown Widow doe not just predate the Black Widow because of prey scarcity, but the bold Brown Widow actively hunts the shy Black Widow, preferring it to other spider species as prey.

LINK LINK 2 LINK 3

Latrodectus species tend to prefer dry habitats and in their native countries they're are often found around buildings. Where found away from human habitations their typical habitats can include wood stacks, rock piles, rodent burrows, and hollow tree stumps.

Like other Black Widow species the Brown Widow is not an aggressive spider towards humans and even when you invade its web its reaction is usually to either retreat to its place of hiding or drop to the ground and play dead. Bites to humans usually only occur as a result of the spider being accidentally trapped against human skin. Adult female specimens have also been known to defend their egg-sacs. The much smaller male of the Brown Widow Spider usually poses no risk to humans at all as its fangs are too small to penetrate most human skin.

Latrodectus geometricus produce very distinctive spiky egg-sacs. The only other Latrodectus egg-sac, that I'm aware of, that can sometimes be mistaken is the slightly spiky egg-sac of the Asian Black Widow species, Latrodectus elegans. Research published in 2019 proved that the egg-sacs of Latrodectus geometricus have antibacterial properties that protect the eggs within from bacteria or fungal growth. - LINK

One Latrodectus geometricus egg-sac can contain as many as 120-150 eggs. Fertilised female Brown Widows produce an average of 23 egg-sacs during their lifetime. By comparison the egg-sacs of the Western Black Widow (Latrodectus hesperus) can contain around 300 eggs, but the female spider will only produce up to 10 egg-sacs in her lifetime. Most other species of Black Widow do not produce the distinctive spiky egg-sacs produced by the Brown Widow, and it is these unique egg-sacs that make this species easy to identify in the field. Fertile eggs of the Brown Widow usually take 14-21 days to hatch, but the spiderlings can remain hidden away within the egg-sac from just a few days to another month after hatching. It's not uncommon for the Brown Widow to create several egg-sacs at a time, with as few as just one or more of those actually containing fertile spider eggs. The newly hatched spiderlings are very pale with no visible patterning. They will moult before leaving the egg-sac. By their second moult the spiderlings start to display the typical hourglass marking on their underside. Initially this marking is white and can be quite difficult to see. After emerging from the egg-sac the spiderlings will stay close by in a group for some time, during which time cannibalism is common. They eventually disperse by ballooning in the wind on threads of silk.

The Widow spiders get their name from the behaviour sometimes associated with Black Widow Spiders, where the female spider may eat her male partner during, before or after copulation. This practice is common with the Brown Widow Spider. Where it was once thought that this was an aggressive act on the part of the female, studies of the Brown Widow now lead arachnologists to believe that this behaviour is similar to the matriphagy observed with other species of spider, but now on the part of the male, as he offers himself as a sacrifice to the female for the growth and development of his offspring now inside the female. During copulation the male has frequently been observed to rotate himself 180 degrees and place his abdomen directly in front of the jaws of the female. This behaviour has also been recorded with the Australian Black Widow species, the Red Back Spider, Latrodectus hasselti.

LINK 1 LINK 2 LINK 3 LINK 4 LINK 5 LINK 6 BITE

The Brown Widow, Latrodectus geometricus, was originally believed to be present in Madagascar too. Further analysis of the Brown Widow in Madagascar revealed it to be distinctive enough to be classed as a comletely separate species, Latrodectus obscurior. Latrodectus obscurior is also found in Cape Verde too, an Island country off the west coast of Africa. Latrodectus menavodi, the Madagascan Black Widow, is the second Latrodectus species to be found in Madagascar.

Is the Brown Widow found in Europe?

Yes, the spread of the Brown Widow has now reached Europe, and Latrodectus geometricus is established in both Cyprus and Turkey. In Duncan McCowan's 2014 book "60 Cypriot Spiders" the Brown Widow was already referred to as the most common Latrodectus species in Cyprus. The author also claimed Latrodectus geometricus had been well established for years around a play area at Larnaca's tourist beach. Latrodectus geometricus was officially listed in the "Spiders of Cyprus" catalogue in 2019. LINK

In 2023 I was able to personally confirm for myself that Latrodectus geometricus is now widely established, and extremely common, in Cyprus.

For further information on the spread of the introduced Latrodectus geometricus in Europe visit this page of my website - The Brown in Cyprus

Are supermarkets using Widow Spiders as a form of biological pest control?

With Latrodectus specimens, especially dead specimens, being found fairly regularly as accidental stowaways hidden amidst imported fruit, supermarkets have in the past been accused of using Widow Spiders as a form of biological pest control within their crops. This is something that supermarkets have always strongly denied, but is there any truth to these rumours? In my opinion the idea that any supermarket would deliberately encourage or even introduce highly venomous species within their crops is quite frankly absurd. Crops are often protected by deliberately introduced biological control species, including spiders, but the species used are always harmless to humans.

Crops such as grapes are often picked in their home countries by hand. Farmers of these crops would not risk the health and lives of their workers by introducing such hazards. I also believe there is no chance that Supermarkets would ever risk their UK customers finding a highly venomous species within their produce. Measures are taken to prevent non-native species from reaching the UK within imported fruit and veg. Produce is regularly treated with toxic pesticides, and any invertebrate hitchhikers that manage to survive the pesticides usually die during the refrigerated transport of the produce as it travels to the UK. The BBC covered the story back in 2002. - BBC News - "Tesco Denies Using Deadly Spiders"

Are Black Widows Venomous or Poisonous?

The term "poisonous" is generally reserved for things that are toxic when ingested, and the term for wildlife that injects its poison is "venomous". So does this mean that spiders aren't poisonous, but they are venomous? In most cases yes, but not always. Recent studies have shown that adult Latrodectus species are not only venomous but they're also poisonous too, when eaten by predators. Testing on mice, rats and rabbits has shown that body-parts, including the legs and abdomen, of Latrodectus species can be deadly when eaten, due to the toxins these species carry. Tests on cockroach subjects confirmed that Latrodectus can also be deadly poisonous to insect predators too.

But the extent of their toxicity goes well beyond the adult spiders. Laboratory tests have shown that both juveniles and even the eggs of Latrodectus tredecimguttatus also contain highly toxic proteins, that can be deadly when eaten. It is highly likely that these levels of toxicity extend to the other Latrodectus species too. Interestingly, similar tests on other species of spider, including the highly venomous Recluse Spider, Loxosceles species, showed no toxicity at all when fed to mice. LINK LINK 2

These toxins present in Black Widows certainly don't deter all invertebrate predators. The Brown Widow actively hunts Black Widow spiders. Even the much smaller Candy-Stripe Spider has been recorded invading the webs of Black Widows and feeding on their spiderlings. LINK

Dangerous Wild Animal Act Species

In the UK there are only four genus of spider that fall under the Dangerous Wild Animals Act 1976. These include the certain types of Wandering Spiders (Phoneutria genus), the Sydney Funnel-web Spider (Atrax genus), the Recluse Spiders (Loxosceles genus) and the Widow Spiders (Latrodectus genus). All other species of spider are not considered by UK Law to have a bite significantly dangerous to humans and can therefore be kept in captivity without restrictions.

A DWAA licence needs to be obtained from the local council to keep DWAA species at any premises for longer than a 72 hour continuous period. A DWAA licence is not required to collect or transport DWAA species to a licence holder.

An Account of a Black Widow Bite

In February 2024 Benata Smit, a researcher in South Africa, was bitten by a Black Button Spider (Latrodectus sp.), that was being held captivity. The sub-adult female specimen, believed to be Latrodectus indistinctus, was being studied in captivity and had not yet been formally identified as it hadn't reached maturity at this stage. Latrodectus species are usually shy and typically show no aggression when treated with respect. On this occasion the spider, that was originally captured from the wild in South Africa during October 2023, was already stressed after being transported from one location to another, to be studied in captivity. The spider was immediately defensive when taken out of its enclosure to be photographed, and it bit the researcher on her finger:

"I had the fortunate (for me) or unfortunate experience of having to endure, as the Africans would say, "big poison comes in small bottles". I was bitten by this beautiful black button spider (Latrodectus sp.). It’s important to note that the bite wasn’t caused by any harm imposed on the spider, as we generally assume that spiders have to be squashed / harmed before they bite. It was a humbling experience to say the the least.

It took a total of 25 minutes for me to experience the full brunt of the envenomation. She bit me on my left ring finger. In 5 min after she bit me my left elbow and shoulder started to pain. Another 5min and I started having trouble breathing. I was rushed to hospital and on arrival I couldn't use my legs. I had a typical case of Latrodectism where all my muscles started to contract; the pain was intense. It's a kind of pain you can't explain to anyone because it's so unique. When I arrived at the ER the doctor was very quick to react, even though it was their 1st black button spider bite case. They handled it very professional and knew exactly what to do to keep me calm and comfortable. Unfortunately there was no anti-venom at this specific hospital so they had to phone another hospital for anti-venom. The anti-venom arrived half an hour later. But in that half an hour it felt like I was dying. I was given a whole cocktail of pain and other meds to make sure I don't have any allergic reaction to the venom or anti-venom. I was administered the anti-venom immediately after it arrived. It took only 2 minutes for the anti-venom to take effect. I couldn't believe how quickly all the symptoms disappeared.

I was kept in High care for 24 hours, to be monitored and to make sure I don't have any allergic reaction to any of the meds I was given." - LINK

Black Widow further information:

Widow Spiders in the Americas - LINK LINK 2

List of Latrodectus species - LINK LINK 2

Further reading: National Library of Medicine - A review of Latrodectus species,

Widowman - Widow Spiders in the USA

CLICK HERE FOR: 1 - SPIDERS, 2 - LARGE ORB-WEAVERS 3 - JUMPING SPIDERS 4 - FALSE WIDOW SPIDERS 5 - CRAB SPIDERS

6 - ORB-WEAVERS 7 - NON-NATIVE SPIDERS 8 - SPIDERS WEBS 9 - CAVE SPIDERS 10 - PURSE-WEB SPIDERS