False Widow (Steatoda nobilis)
Britain's most talked-about spider is a Macaronesian immigrant that arrived in a fruit crate. The noble false widow has a bulbous brown abdomen patterned with cream, reddish-orange legs and a scaffold web spun around window frames, porches and garden walls. It is the only spider in the British Isles that regularly causes bites worth a doctor's attention, and also the most consistently exaggerated one.
By Dr Richard J. Pearce (PhD)Published November 29, 2018Updated September 13, 2026✓ Reviewed by Dr. James Watuwa
In this guide
Physical description and identification
The noble false widow is a solidly built Steatoda spider with a shape people instinctively read as dangerous: a large, shiny, almost spherical abdomen on comparatively short legs. The colour is brown rather than black, and the pattern on top of the abdomen is what separates it from a true widow at a glance. Mistaken identity is the biggest single source of false widow reports.
Adults
- Size: mature females have a body length of roughly 9–14 mm, which with the legs makes a spider a little wider than a two-pence coin. Males are slimmer and longer-legged at about 7–11 mm. Reports of 15 mm females sit at the extreme upper end for the species.
- Colour: the abdomen is glossy chestnut to dark chocolate brown, usually with a pale cream band across the front edge and a row of cream chevrons down the middle, often described as skull-shaped. The legs are noticeably reddish-orange to amber — never the lacquer black of a widow. Older females darken and can lose most of the pattern, which is when confusion peaks.
- Eyes: eight eyes in two rows of four on a low, rounded head region. Eyesight is poor even by spider standards, and the animal relies on vibrations in its silk; our guide to spider eyes explains why tangle-web spiders can afford such weak vision.
- Distinctive features: a comb of curved bristles on the hind tarsi for flinging silk over prey, and the habit of hanging upside down. Crucially, there is no red or orange hourglass underneath; a well-defined hourglass means a true widow, not this species.
Eggs and egg sacs
Females mate mainly between May and July and hang a series of pale cream, loosely woven, roughly spherical sacs in the densest part of the web, guarding them closely. Each sac commonly holds one to two hundred eggs, and a female can build three or more in a season. Unlike the older accounts claiming she dies after her first sac, she typically survives to lay again over successive years.
Spiderlings
In warm conditions eggs hatch in roughly two to four weeks rather than months. The spiderlings cluster around the sac briefly, feeding on yolk and moulting once, then disperse a short distance on silk threads. Growth is slow: most need several months to a year and six to eight moults to mature, so juveniles, subadults and adults share a building at the same time. Shedding the exoskeleton is described on our page about spider molting.
The web
The web is a three-dimensional scaffold of tough, irregular silk with no recognisable pattern, built into a corner, a crack in brickwork, a window recess or the angle of a fence panel. A silk retreat sits at the back, deep in a crevice where the spider spends the day. From the tangle, taut vertical lines run to a solid surface and carry glue droplets at their lower ends, so a walking insect is caught and lifted clear of the ground. See our overview of spider webs for how this differs from the flat spirals of orb weavers.
Where the false widow spider lives
Steatoda nobilis is native to the Atlantic archipelagos of Madeira and the Canary Islands. It was first recorded in Britain at Torquay in Devon in 1879, almost certainly arriving in cargo from the Canaries, and remained a coastal curiosity for a century. Since the 1980s it has expanded rapidly and is now common across southern and central England, spreading northwards, and firmly present in Ireland since the late 1990s. Milder winters and its ability to live on the warm outer walls of heated buildings are both cited as reasons.
Beyond the British Isles it is established in Portugal, Spain, France and Italy, in coastal California since 2011, and in Chile, the first South American record in 2016. Further records from Colombia, Ecuador and Turkey make it one of the most successful invasive spiders on earth.
Its preferred habitat is anything vertical, sheltered and man-made: window and door frames, porches, sills, conservatories, sheds, garages, garden walls, fences and bins, usually above waist height. The older claim that the species rarely comes indoors is no longer accurate for Britain and Ireland, where it is a routine find in conservatories, garages, bathrooms and behind furniture, alongside other common house spiders.
Are false widow spiders venomous?
Yes. Every spider in the family uses venom to kill prey, but Steatoda nobilis is unusual among European spiders in that its venom has a measurable effect on people. Laboratory work shows it shares a significant proportion of its toxin components with true Latrodectus widows, including relatives of the latrotoxins behind latrodectism. The milder syndrome it produces has its own name, steatodism.
Severity, though, is on a different scale. Pain is usually local and self-limiting, systemic illness is uncommon, and there is no credible record of a death caused by this species anywhere in its range. Where symptoms have been severe enough to warrant it, hospitals have successfully used Latrodectus antivenom — direct evidence of the chemical similarity between the two genera. The false widow deserves respect and sensible handling, not the alarm that periodically surrounds it.
Can false widow spiders bite?
They can. False widows are shy and their first response to a person is to drop out of the web and run, so bites almost always happen when the spider is trapped against skin — inside clothing taken off a line, in bedding, in a work glove, or when a hand goes blindly into a crevice. Only a minority of reported bites are ever confirmed with the spider in hand, so bite statistics for this species should be read cautiously.
A typical bite is felt as a sharp prick or, quite often, not felt at all. Within fifteen to sixty minutes the site becomes warm, red and swollen, frequently with two small puncture marks and a raised weal, and the pain may radiate along the limb. Tingling, burning and localised sweating are reported, and the area often discolours to a dull bruised tone over the following hours. Less often people develop nausea, headache, malaise or joint aching for a day. Most cases settle within one to three days with simple analgesia.
What to do after a suspected false widow bite: wash the site thoroughly with soap and water, apply a cold pack, keep the limb elevated and take an ordinary painkiller. Do not scratch, cut, burn or apply folk remedies, and do not use a pressure bandage. Photograph the spider if you can, since correct identification matters more than anything else. Seek medical care if the pain is severe or spreading, if redness expands over hours with increasing heat and pus (secondary bacterial infection, the main real complication), or if you have difficulty breathing, a widespread rash or faintness suggesting an allergic reaction.
Two points are usually lost in reporting. Ordinary wound infection — not venom — is behind most of the dramatic photographs of blackened, ulcerated wounds attributed to this spider. And correctly identified false widow bites in Britain and Ireland number in the tens of confirmed cases per year, not the thousands sometimes claimed.
Ecological importance and behaviour of the false widow spider
The false widow is a nocturnal sit-and-wait predator that spends the day deep in its retreat and moves to the hub of the web after dark. Its gum-footed lines are effective against heavily armoured prey, and its diet includes woodlice, beetles, flies, wasps, ants and cockroaches. It also takes other spiders readily, which is part of why its spread has reduced native tangle-web populations around buildings.
Unusually large prey: published records from Britain and Ireland include a false widow subduing a pygmy shrew, plus separate cases of bats and small lizards caught in the webs — all documented by researchers rather than anecdote. The capacity comes from the gum-footed design, which does the lifting, combined with potent venom.
Natural predators: birds, particularly wrens and tits working over walls and fences, take exposed adults. Parasitoid and spider-hunting wasps attack adults and egg sacs, and cellar spiders invade the webs of smaller individuals, as summarised on our page about what eats spiders.
Seasonal behaviour: adults occur all year in sheltered positions but become conspicuous in late summer and autumn, when females are full-sized, males are wandering and both sexes move closer to heated buildings. That is when almost all sightings and bite reports occur.
Relationship with humans: a competent urban insect predator, and a nuisance only when it webs up a doorway or bedroom. Vacuuming webs, sealing gaps around frames and vents, shaking out stored clothing and wearing gloves when clearing sheds removes nearly all bite risk without chemicals.
Similar spiders and how to tell them apart
| Spider | How it differs from the noble false widow |
|---|---|
| False black widow (Steatoda grossa) | Similar build but purplish-black to dark brown with faint pale crescents and darker legs. Far more often found deep inside houses, in cellars and under furniture. |
| Rabbit hutch spider (Steatoda bipunctata) | Smaller and rounder, reddish-brown with a pale line down the middle of the abdomen and a leathery sheen. Associated with sheds, hutches and outbuildings. |
| Triangulate cobweb spider (Steatoda triangulosa) | Much smaller at 3–6 mm, with pale yellow legs and a zigzag of white and purple-brown triangles instead of chevrons. |
| Mediterranean black widow (Latrodectus tredecimguttatus) | A true widow: matte black with up to thirteen red spots above and a genuinely dangerous bite. Lives in grassland and scrub, not on house walls. |
| Southern black widow (Latrodectus mactans) | Glossy jet black with black legs and a clean red hourglass underneath. A sharp hourglass means it is not a false widow. |
| Common house spider (Parasteatoda tepidariorum) | Also a cobweb spider, but dull grey-brown and mottled rather than glossy, with banded legs and a softer, dustier web. |
Quick facts
| Other names | Noble false widow, false widow spider |
|---|---|
| Distribution | Native to Madeira and the Canary Islands; established across Britain and Ireland, western Europe, coastal California, Chile and Turkey. |
| Habitat | Vertical man-made surfaces: window and door frames, porches, sills, conservatories, sheds, garages, walls, fences and bins, usually above waist height. |
| Diet | Woodlice, beetles, flies, wasps, ants, cockroaches and other spiders; occasionally small vertebrates trapped in the web. |
| Lifespan | Females commonly live several years and lay repeatedly; males usually survive around a year to eighteen months and die within months of maturing. |
| Predators | Birds, spider-hunting and parasitoid wasps, cellar spiders, centipedes and shrews. |
| Web | Irregular three-dimensional scaffold with a crevice retreat and sticky gum-footed trap lines anchored below. |
| Danger | Moderate. Bites cause steatodism — local pain, swelling and occasional systemic upset — but are not life-threatening. |
| IUCN status | Not evaluated. Abundant and still expanding in its introduced range. |
Did you know?
- The species reached Britain in fruit shipments from the Canary Islands, the first specimen being collected at Torquay in 1879 — an old introduction, not a recent arrival.
- Hospitals treating unusually severe bites have used true widow antivenom successfully, confirming laboratory findings that the two genera share related toxins.
- Researchers documented a noble false widow killing and eating a pygmy shrew, a mammal many times its own mass, alongside records of bats and lizards taken in its webs.
- In October 2018 several schools in east London closed temporarily after false widow infestations, often cited as the high point of British spider panic.
- It is now considered one of the world's most invasive spiders, and a case study in how heated buildings let a subtropical animal colonise cool climates.
In summary, the noble false widow is a brown, cream-marked cobweb spider with orange legs and a painful but rarely serious bite. Look for the chevrons, the reddish legs and the absence of a red hourglass, keep the webs out of doorways and bedrooms, and treat spreading redness with heat and pus as a wound infection needing a doctor rather than as spider venom.
Frequently asked questions about the false widow
What does a female false widow spider look like?
She has a shiny, almost spherical chestnut to dark brown abdomen roughly 9 to 14 mm long, patterned with a pale cream band at the front and a row of cream chevrons, and distinctly reddish-orange legs. She hangs upside down in an untidy web and has no red hourglass underneath.
How big do false widow spiders get?
Females reach about 9 to 14 mm in body length, which with the legs makes them a little wider than a two-pence coin. Males are slimmer and longer-legged at roughly 7 to 11 mm and carry swollen pedipalps. Both sexes are far smaller than the media usually suggests.
How do you tell a false widow from a real black widow?
Check the underside and the legs. A true widow has a sharply defined red or orange hourglass beneath a glossy black abdomen and uniformly black legs. A false widow is brown with cream chevrons on top, reddish-orange legs and no clean hourglass mark below.
Are false widow spiders aggressive towards people?
No. They are shy and their standard response to disturbance is to drop from the web and hide. Bites happen when a spider is trapped against skin, most often in clothing taken from a line, in bedding, or when a hand is pushed into a crevice. They do not chase or jump at people.
How painful is a false widow spider bite?
Most bites cause a sharp prick followed within an hour by warmth, redness, swelling and pain that may radiate along the limb. Some people get tingling, localised sweating, nausea or malaise. Symptoms usually settle within one to three days with a cold pack and ordinary painkillers.
Can a false widow bite cause a serious infection?
Secondary bacterial infection is the main real complication, and it is a wound problem rather than a venom effect. If the redness keeps expanding over hours, the area becomes hot and tight, or pus appears, see a doctor promptly — those dramatic ulcerated wound photographs almost always involve infection.
How many eggs does a false widow spider lay?
Each pale, loosely woven sac usually holds around one to two hundred eggs, and a female can build three or more sacs in a season, mostly between May and July. She guards them in the densest part of her web and, contrary to older accounts, normally survives to lay again in later years.
What does a false widow web look like?
It is an irregular three-dimensional scaffold with no pattern, built into a corner, crevice, window recess or fence angle, with a silk retreat at the back and taut lines running down to a solid surface. Only the lower tips of those lines are sticky, so crawling insects are caught and lifted.
Where did false widow spiders come from?
The species is native to Madeira and the Canary Islands. It reached Devon in fruit cargo by 1879, stayed a coastal curiosity for a century, then expanded rapidly from the 1980s. It is now established across Britain, Ireland, western Europe, coastal California, Chile and beyond.
Why do I see so many false widows in autumn?
Adults are present all year, but in late summer and autumn the females reach full size, the males leave their webs to find them, and both sexes move onto the warm outer walls of heated buildings. That combination makes them suddenly conspicuous and drives most sightings and bite reports.
References
- World Spider Catalog (2026). Steatoda nobilis (Thorell, 1875). Natural History Museum Bern. wsc.nmbe.ch/spec-data/46135/taxon
- Dunbar, J. P., Sulpice, R. & Dugon, M. M. (2019). The kiss of (cell) death: can venom-induced immune response contribute to dermal necrosis following arthropod envenomations? Clinical Toxicology 57(8): 677–685. doi.org/10.1080/15563650.2019.1578367
