False Black Widow, Cupboard Spider, Comb-footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A medium-sized spider with a shiny, bulbous abdomen and a smaller cephalothorax. The surface is smooth and lacks the dense hairs found on wolf spiders. It possesses an oval-shaped opisthosoma (abdomen) and characteristic 'comb' on the tarsi of the fourth pair of legs for silk manipulation.
Size Estimate
Body length 6-10 mm for females; leg span approx 15-25 mm. This specimen appears to be an adult or sub-adult.
Coloration & Markings
Dark purple-brown to blackish-plum base color. Often features a pale crescent or 'D' shaped mark on the anterior of the abdomen, sometimes with additional light-colored spots or chevrons along the dorsal midline. Unlike true black widows, it lacks a red hourglass.
Web Type
Tangle web or cobweb. A messy, three-dimensional structure of high-strength silk typically built in corners, under furniture, or in dark crevices.
Eye Arrangement
8 eyes in two rows of four. The arrangement is typical of Theridiids, focusing on detecting vibrations rather than sharp distance vision.
Leg Characteristics
Relatively long, slender legs compared to the body. Legs are usually the same dark color as the cephalothorax, sometimes slightly reddish-brown, and may show faint banding in juveniles.
Venom & Safety Information
Venom Information
Contains latrodectine-like neurotoxins, but much less potent than true widows (Latrodectus). Bites may cause localized pain and minor systemic symptoms but are rarely severe.
Medical Significance
Low to Moderate. While not life-threatening, a bite can cause localized swelling, nausea, and 'steatodism' (sweating and muscle aches). Treatment is usually symptomatic with ice packs and pain relief.
Safety Recommendations
Relocate using the 'cup and card' method if found inside. Wear gloves when cleaning out dark areas like garages or woodpiles to avoid accidental defensive bites.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found worldwide. Prefers dark, undisturbed areas such as garages, basements, sheds, and crawl spaces. Often lives in close proximity to humans.
Behavior & Temperament
Sedentary and nocturnal. They are exceptionally shy and prone to retreating or 'playing dead' (thanatosis) when disturbed. They are not aggressive and vary rarely bite unless squeezed or crushed.
Diet & Prey
Generalist predators feeding on various insects, including woodlice, crickets, flies, and even other spiders. They use sticky silk to entangle prey much larger than themselves.
Seasonal Activity
Active year-round in indoor or protected environments; mating and egg production typically peak in spring and summer.
Description
An inconspicuous inhabitant of shadowy corners, this spider is often mistaken for its more famous cousin, the Black Widow. It is a master of pest control, constructing strong silk snares that capture unwanted household insects.
Key Features
Shiny bulbous abdomen, dark color without red markings, pale crescent on the anterior abdomen, and a preference for dark corners.
Similar Species
Latrodectus (True Widow spiders) - distinguished by the red hourglass and deeper black color; Steatoda nobilis (Noble False Widow) - distinguished by 'skull' markings on the abdomen.
Life Cycle
Females produce several round, white/cream papery egg sacs throughout the year. Spiderlings emerge and may disperse via ballooning. Average lifespan is 1 to 6 years for females.
Ecological Importance
Excellent natural pest control. They significantly reduce populations of invasive or annoying synanthropic insects in human dwellings.
Conservation Status
Not evaluated by IUCN; widely distributed and common worldwide with stable populations.
Interesting Facts
In some regions, they are known to prey on actual Black Widow spiders. They are often used in movies as 'stunt' spiders because they look like dangerous species but are much safer for handlers.
Photography Tips
Focus on the dorsal (top) of the abdomen to capture identifying crescent marks. Use a flashlight to highlight the glossiness of the body against the dark background.
Identified: 2026-07-20T21:09:05.633812