False Black Widow, Cupboard Spider, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A medium-sized spider with a bulbous, glossy, teardrop-shaped abdomen and a smaller, oval cephalothorax. The surface is smooth and shiny, often resembling the texture of polished glass. Females are much larger and more robust than males.
Size Estimate
Females typically 6-11mm body length; males 4-6mm. Total leg span often reaches 15-25mm. This specimen appears to be an adult or sub-adult.
Coloration & Markings
Dark purple-brown to nearly black base coloration. The abdomen features a pale, crescent-shaped marking at the anterior end and several light-colored spots or chevrons down the midline, which often fade as the spider matures.
Web Type
Tangle web or cobweb; a messy, three-dimensional scaffold of sticky silk built in dark corners, under furniture, or in crevices.
Eye Arrangement
Eight eyes arranged in two rows of four. The lateral eyes are typically touching or very close to one another, a common trait of the Theridiidae family.
Leg Characteristics
Relatively long, slender legs compared to the body. They are typically reddish-brown to dark brown and lack the distinct banding seen in some other Steatoda species. The fourth pair of legs features a 'comb' of serrated bristles used to wrap prey.
Venom & Safety Information
Venom Information
Neurotoxic venom used to paralyze prey. While not nearly as potent as a true Black Widow (Latrodectus), it can cause localized pain and minor systemic symptoms (steatodism).
Medical Significance
Low to moderate danger. Bites are rare and usually occur only if the spider is pressed against skin. Symptoms include localized pain, swelling, and occasionally nausea or lethargy. Medical attention is rarely needed unless symptoms persist or an allergic reaction occurs.
Safety Recommendations
Use a cup and paper to relocate them outdoors if they are unwanted. Wear gloves when cleaning dark, undisturbed corners of garages or basements to avoid accidental bites.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found worldwide. Highly synanthropic, preferring dark, undisturbed indoor areas like basements, crawl spaces, garages, and cupboards.
Behavior & Temperament
Sedentary, nocturnal, and extremely shy. They spend most of their time tucked into a retreat near their web. They are not aggressive and typically play dead or run away when disturbed.
Diet & Prey
Generalist predators feeding on crawling insects, sowbugs, and even other spiders, including true black widows. They use their sticky webs and 'wrap-attack' technique to subdue larger prey.
Seasonal Activity
Active year-round in indoor environments. Outside, they are most visible from late summer through late autumn during the mating season.
Description
The False Black Widow is a common household resident often mistaken for its more dangerous relatives. Known for its glossy finish and preference for dark corners, it acts as a very effective natural pest controller within the home environment.
Key Features
Glossy bulbous abdomen, pale anterior crescent mark, absence of a red hourglass, and a tangled cobweb.
Similar Species
Latrodectus species (Black Widows) which have a red hourglass; Steatoda nobilis (Noble False Widow) which has a 'skull' pattern on the abdomen.
Life Cycle
Females produce several white, papery, spherical egg sacs over their lifetime. Spiderlings disperse via ballooning. Females can live up to 5-6 years; males have significantly shorter lifespans.
Ecological Importance
Serves as an important apex predator in indoor micro-ecosystems, controlling populations of woodlice, flies, and various household pests.
Conservation Status
Not evaluated by the IUCN; widespread and common with stable populations.
Interesting Facts
This species is known to prey on true Black Widows as well as highly venomous spiders like the Mediterranean Recluse, making them beneficial house guests for pest management.
Photography Tips
Focus on the dorsal abdominal pattern and the glossiness of the cephalothorax. Use a macro lens or a light source from the side to highlight the crescent mark without creating harsh glares on the shiny body.
Identified: 2026-07-21T02:56:12.549484