F
Species Profile

False Widow Spider

Steatoda nobilis

Tangle-web builder, not a true widow
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False Widow Spider Distribution

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False Widow Spider

At a Glance

Wild Species
Also Known As False widow, False black widow, False black widow spider
Activity Nocturnal+
Lifespan 2 years
Status Not Evaluated
Did You Know?

Adult size: females ~0.95-1.4 cm body length; males ~0.7-1.0 cm (Nentwig et al., araneae.nmbe.ch).

Scientific Classification

The Noble False Widow (Steatoda nobilis) is a cobweb spider in the family Theridiidae, closely related to true widows (Latrodectus) but generally less medically significant. It builds messy tangle webs and commonly occurs around buildings and gardens in parts of Europe and other introduced regions.

Kingdom
Animalia
Phylum
Arthropoda
Class
Arachnida
Order
Araneae
Family
Theridiidae
Genus
Steatoda
Species
Steatoda nobilis

Distinguishing Features

  • Cobweb/tangle-web builder (Theridiidae) with a rounded abdomen
  • Often shows pale/cream marbled markings on a dark brown abdomen (pattern varies widely)
  • Frequently found in and around buildings and other sheltered structures
  • Resembles widow spiders (Latrodectus) superficially, but lacks the classic red hourglass underside marking typical of many true widows

Did You Know?

Adult size: females ~0.95-1.4 cm body length; males ~0.7-1.0 cm (Nentwig et al., araneae.nmbe.ch).

It's a "comb-footed" spider (Theridiidae): the hind legs have a serrated comb used to flick sticky silk over prey.

Webs are messy 3-D tangles with "gumfoot" lines that snag walking insects-common around fences, sheds, window frames, and garden clutter.

Abdominal markings are highly variable; many individuals show pale cream marbling, but pattern is not reliable for a single 'standard' look.

Documented as an opportunistic predator that can take other spiders and, rarely, small vertebrates (e.g., geckos/lizards) in urban settings (Dunbar et al., 2020, Biological Invasions).

Bites can cause a syndrome called "steatodism" (pain, redness, sometimes systemic effects), generally milder than true widow (Latrodectus) envenomation (Isbister & Gray, 2003, Toxicon).

Unique Adaptations

  • Comb-foot (Theridiidae hallmark): a row of serrated bristles on tarsus IV that lets the spider 'comb' and fling sticky silk for fast immobilization.
  • Sticky gumfoot lines: specialized capture threads that attach to surfaces and snap prey upward into the web when they struggle.
  • Venom tuned for small arthropods: potent on insect prey; in humans it usually causes localized pain/swelling, with occasional wider symptoms (reported clinically as steatodism) (Isbister & Gray, 2003).
  • Urban tolerance: readily uses human-made crevices and stable microclimates (walls, sheds, railings), aiding establishment in towns and coastal cities.
  • Pattern variability: variable abdominal marbling can help break up the outline against bark, stone, and man-made surfaces (avoid relying on a single 'typical' pattern for ID).

Interesting Behaviors

  • Tangle-web engineering: builds an irregular 3-D cobweb plus taut "gumfoot" threads that adhere to and trip ground-walking prey.
  • Sit-and-sense hunting: often waits in a retreat and reads prey/courtship signals through web vibrations before rushing to bite and wrap.
  • Rapid silk "throwing": uses the comb on the 4th legs to cast sticky silk over struggling prey, reducing risk from spiny or biting insects.
  • Generalist, synanthropic foraging: commonly hunts flies, ants, woodlice, and other spiders around buildings and gardens; will also scavenge trapped prey.
  • Egg-sac guarding: females typically remain in the web, guarding egg sacs and maintaining the capture threads over extended periods.
  • Nocturnal activity peaks: many individuals are most active after dusk, when they repair web lines and respond to vibrations.

Cultural Significance

In the UK and Ireland, Steatoda nobilis is a well-known house and garden spider. Media reports of 'false widow' bites led to pest control calls and public interest. It is often used as an example of how trade and urban heat help invasive spiders spread.

Myths & Legends

Name lore: the epithet "nobilis" ("noble") comes from its original scientific description (Thorell, 1875), and the English name "false widow" grew from its widow-like glossy body and its family relationship to true widows (Latrodectus).

Modern urban legend in Britain and Ireland: tabloids called the noble false widow 'Britain's most dangerous spider,' telling dramatic stories of bites and infestations in schools, hospitals, and homes that became local folklore.

In parts of Europe, household spiders are seen as signs of saving, patience, or luck. Urban species like Steatoda nobilis are often included in these old house spider beliefs.

People use tales of Arachne, Anansi, and Spider Grandmother when teaching about cobweb spiders like the Noble False Widow (Steatoda nobilis), to connect their tangled webs with fate, skill, and cleverness.

Conservation Status

NE Not Evaluated

Has not yet been evaluated against the criteria.

Population Increasing

Life Cycle

Birth 120 spiderlings
Lifespan 2 years

Lifespan

In the Wild
1–3 years
In Captivity
2–4 years

Reproduction

Mating System Polygynandry
Social Structure Solitary
Breeding Pattern Transient
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Steatoda nobilis males leave their webs and roam to find females; mating is brief and by chance. Males transfer sperm with pedipalps; females store it in spermathecae and can mate multiple times. Females make egg sacs, no helpers, and no lasting pair bonds; sexual cannibalism is not typical.

Behavior & Ecology

Social Aggregation Group: 1
Activity Nocturnal, Cathemeral
Diet Insectivore Flying insects commonly intercepted in the tangle web (especially flies such as houseflies), reflecting its frequent occurrence on buildings and in gardens.
Seasonal Hibernates

Temperament

Non-social, web-based sit-and-wait predator; spends extended periods in/near a retreat connected to the tangle web
Territorial/defensive when disturbed in the retreat; most bites are associated with pressing/trapping against skin rather than pursuit (clinical/incident summaries for S. nobilis emphasize defensive context of bites in synanthropic environments)
Opportunistic predator with broad prey spectrum; will take a wide range of arthropods captured in the tangle web (field observations and invasive-range accounts note generalist predation)

Communication

Web-borne vibration signaling: courtship and threat/assessment via patterned tapping/plucking transmitted through silk General theridiid mechanism reviewed in Foelix, 2011; applies to Steatoda mating in web
Chemical communication via silk/pheromones: males use female silk cues to locate receptive females; contact chemoreception through tarsi/pedipalps Common in araneomorph spiders; reviewed in Foelix, 2011
Tactile communication during courtship: leg/pedipalp contact and controlled web movements to reduce female aggression and facilitate mating Theridiid courtship modality; reviewed in Foelix, 2011

Habitat

Biomes:
Mediterranean Temperate Forest Temperate Grassland Temperate Rainforest
Terrain:
Coastal Island Hilly Plains Valley Rocky Sandy +1
Elevation: Up to 3280 ft 10 in

Ecological Role

Generalist synanthropic arthropod predator (tangle-web spider) that can suppress nuisance insects around human structures but may also exert predation pressure on native arthropods where introduced and abundant.

Predation on pest insects around buildings and gardens (biological control) Food-web support as prey for spider-eating predators/parasitoids and as a predator of diverse invertebrates Potential negative impact on local arthropod communities (including other spiders and beneficial insects) in areas where it becomes abundant (invasive/synanthropic contexts)

Diet Details

Main Prey:
Flies Ants and wasps Small beetles Moth True bug Woodlice and pillbugs Other spiders Small vertebrates +2

Human Interaction

Domestication Status

Wild

Steatoda nobilis (Noble False Widow) is a wild cobweb spider, not domesticated. It often lives on and in buildings, making tangled webs in corners and crevices. Females about 0.7–1.4 cm, males about 0.4–1.0 cm; females may live years. Makes many egg sacs. Bites are uncommon; it helps control pest insects and can spread to new areas.

Danger Level

Moderate
  • Bite risk is generally low but non-zero in homes (most bites occur when the spider is trapped against skin).
  • Envenomation can cause marked local pain, redness, swelling; some cases report blistering and prolonged discomfort.
  • Occasional systemic symptoms have been reported (e.g., nausea, malaise, headache, radiating pain), typically less severe than true widow (Latrodectus) envenomation.
  • Secondary infection risk from any bite/wound (especially if scratched or not cleaned).
  • Allergic reactions are possible but uncommon (as with many arthropod exposures).

As a Pet

Not Suitable as Pet

Legality: Noble False Widow (Steatoda nobilis) is not usually regulated as a pet, but local rules may limit keeping or moving wild-caught or non-native/invasive species. Check wildlife collection, invasive species, and animal welfare laws.

Care Level: Experienced

Purchase Cost: Up to $20
Lifetime Cost: $30 - $200

Economic Value

Uses:
Ecosystem service (arthropod pest suppression) Nuisance/wildlife management (webbing in buildings, perceived infestation) Public health/medical utilization (bite triage/clinical visits) Invasion biology / biosecurity relevance (introduced range management) Education/outreach (arachnology, public engagement)
Products:
  • No established commercial products; value is indirect (pest reduction) and informational (education/research). In some cases, costs arise indirectly via pest-control services, property cleaning, and occasional healthcare consultations following bites.

Relationships

Related Species 7

False black widow
False black widow Steatoda grossa Shared Genus
Rabbit hutch spider Steatoda bipunctata Shared Genus
Mediterranean false widow Steatoda paykulliana Shared Genus
Western black widow Latrodectus hesperus Shared Family
Southern black widow Latrodectus mactans Shared Family
Common house spider
Common house spider Parasteatoda tepidariorum Shared Family
Candy-striped spider Enoplognatha ovata Shared Family

Ecological Equivalents 5

Animals that fill a similar ecological role in their ecosystem

With a similar dark, globular body for identification, the false widow spider is often mistaken for the black widow.

While mistaken for look-alikes, they are two different spiders. Science traces the false widow’s origins to the Canary Islands and Madeira. It’s believed the creature stowed away on transatlantic trips. That’s why today, the false widow’s found all over North Africa, Europe, West Asia and in parts of South and North America.

5 False Widow Spider Facts

Here are some interesting stats about the false widow spider.

  • Though often mistaken for the deadly black widow spider, the false widow is harmless.
  • While the previous fact is backed by science, a new Science Daily report claims not only are the insect’s bites on the rise but the severity can require hospitalization. Still, there is no record showing the false spider can kill.
  • For the layman, identifying spiders isn’t easy. Most actions attributed to the false widow are actually caused by completely different species.
  • The growing frequency of bites is likely because of the species spreading and growing, especially in the U.K.
  • A large portion of bites from this insect seems to take place as the victim sleeps in their home.

False Widow Spider: Species, Types, and Scientific Name

Let’s take a closer look at the false widow.

Species

The false widow spider is a member of a species in the genus Steatoda.

Types

The most common taxonomy in the group is the rabbit hutch, the cupboard, and the noble false widow and the false widow. But there happen to be six species in total.

  • Steatoda nobilis
  • Steatoda grossa
  • Steatoda bipunctata
  • Steatoda albomaculata
  • Steatoda triangulosa
  • Asagena phalerata

Look-alikes for the black widow, the false spider is all brown or black, a rotund family of creatures that grow to about the size of a fingernail.

Scientific Name

The scientific identification name for the false widow is Steatoda grossa.

Appearance: How To Identify the False Widow Spider

The false widow’s body is a glossy chocolate brown. It’s not unusual for the spider to be reddish-brown. The creature lacks the red hourglass marking and instead has unique cream markings. The false widow shares the black widow’s rounded, bulbous abdomen. The false widow is also noticeably smaller than the mature Western black widow.

The female spider has an average length between 0.27 and 0.59 inches. The males are typically in the vicinity of 0.16 to 0.27 inches in length. In general, the spiders weigh around 0.03 ounces.

Beautiful example of a False Widow spider. This species is also dangerous to humans but not life threatening as is the case with the Black Widow or Black Button Spider.

A beautiful example of a False Widow spider. This species is also dangerous to humans but not life-threatening as is the case with the Black Widow or Black Button Spider.

Habitat: Where to Find the False Widow Spider

With origins in the Canary Islands and Madeira before becoming a common species in Ireland‘s urban homes, the false widow is now common all over the globe. Research looking for identification behavior said nearly all bite victims got attacked in their homes as they slept or got trapped in clothing. A number of bites seem to have occurred, oddly enough, while homeowners were working on DIY projects.

Though naturally preferring to be indoors, the false widow is also seen living in cacti, telephone poles, ivy, concrete fence posts, and roadside cuttings. Their invasions also include man-made structures of concrete, steel, and timber in urbanized regions. In California, the spread of the false widow began in urban habitats and moved to natural ecosystems.

The younger spiders live in holes and crevices, making it harder to kill them. They also lean heavily toward living on leaves and vegetation.

Diet: What Do False Widow Spiders Eat?

There are members of the scientific and insect community who argue the false widow spider is beneficial to the household. They patrol the home hunting prey likely to cause long-term damage. When left alone, spiders like these are harmless and they chow on household pests. That’s fruit flies, mosquitoes, house flies, and numerous other pests. And most of these pose a greater threat to human health than the false widow spider.

Prevention: How to Get Rid of the False Widow Spider

While there is an argument to the benefits of having false widow spiders, some people just don’t want the critters around. We can certainly understand why you don’t want these spiders on your business premises.

So, those non-fans of arachnids (and there are many) may want to manage the false widow invasion. Here are a few ways to take care of the situation.

  • Put lavender, plant mint or both, near or underneath your windows. Spiders really don’t appreciate the odor. The taxonomy also implies spiders don’t like citrus. Rub peel from limes or lemons on the window sills and skirt boards, or apply lemon-scented polishes and cleansers to the same surfaces. Other scents rumored to keep false widow spiders out are eucalyptus, peppermint and tea tree oil.
  • Vinegar is supposedly THE spider killer. The acidity burns the spider on contact. Do this with a concoction equal parts water and vinegar. Spray it directly on the spider and should you come across a sac, spray all sides of it liberally.
  • Spiders rely on webs for shelter and food. Removing them is a strong defense to warding them off. Get the corners and areas beneath furnishings as spiders like to hide. Target egg sacs carefully. Once done, discard the debris in the vacuum canister.
  • Insecticide treatments come in liquid and dusting options. Use dusts where they won’t get disturbed by humans or pets, like in the crawl spaces and basements. Liquid treatments are best for others, such as where the arachnids keep their webs. Insecticides should kill present spiders and increases the prevention of new ones.
  • Oil-based solutions are good for targeting egg sacs. Pyrethrin’s a good option. It kills spiders and prevents others from getting into your attic, home or garage.
  • By reducing food sources, you naturally reduce the likelihood of spiders. So, if you have flies, grasshoppers, earwigs, moths or other pests, putting out traps for them is a good idea. This is especially true if you have these creatures in your exterior perimeters.
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Sources

  1. Pen State Extension / Accessed October 5, 2021
  2. kidadl / Accessed October 5, 2021
  3. Lawn Starter / Accessed October 5, 2021
  4. Somerset Live / Accessed October 5, 2021
  5. Wikipedia / Accessed October 5, 2021
  6. Irish Examiner / Accessed October 5, 2021
  7. Orkin / Accessed October 5, 2021
  8. Natural History Museum / Accessed October 5, 2021
  9. Express / Accessed October 5, 2021
A-Z Animals Staff

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False Widow Spider FAQs (Frequently Asked Questions)

The false widow spiders are look-alikes for the deadlier black widow. They both have bulbous, round abdomens. Males are more elongated compared to females and have thinner bodies. The false widow is brownish with pale markings which is how you differentiate it from the black widow.