False Black Widow, Cupboard Spider, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae. Key family characteristics include comb-like setae on the fourth tarsus used to pull silk from spinnerets.
Physical Description
Characterized by a bulbous, globular, glossy abdomen and a smaller cephalothorax. The body texture appears smooth and shiny rather than hairy, with visible sexual dimorphism where females are significantly larger and rounder than males.
Size Estimate
Body length ranges from 6 to 10.5 mm for females and 4 to 6 mm for males, with a total leg span typically around 20 to 30 mm. This specimen appears to be an adult or subadult.
Coloration & Markings
Deep purplish-brown to black base coloration with faint, lighter yellowish or grayish markings, sometimes forming triangular or crescent shapes on the dorsal abdomen. Unlike true black widows, it lacks a red hourglass mark.
Web Type
Irregular tangle web (cobweb) constructed in dark, sheltered locations, composed of sticky, three-dimensional silk scaffolding.
Eye Arrangement
Eight small eyes arranged in two slightly curved, roughly parallel rows typical of the Theridiidae family.
Leg Characteristics
Slender, tapering legs with minimal spination, often matching the dark brown or reddish-brown hue of the cephalothorax.
Venom & Safety Information
Venom Information
Neurotoxic venom (steatotoxin) which is generally mild to humans and used primarily to subdue insect prey.
Medical Significance
Not medically significant. Bites are rare and usually only happen when the spider is trapped against skin. Symptoms are typically mild, consisting of localized pain, redness, and occasional blistering that resolves within days.
Safety Recommendations
Avoid handling with bare hands when cleaning dark corners. Safely relocate individuals outside using a container and a piece of card.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution. Commonly found globally in temperate regions, frequently inhabiting dark corners of buildings, cellars, garages, under logs, and beneath rock overhangs.
Behavior & Temperament
Timid and non-aggressive. They spend most of their time stationary in their webs, dropping or retreating when disturbed rather than attacking.
Diet & Prey
Generalist predators feeding on crawling and flying insects, including woodlice, flies, and occasionally other spiders.
Seasonal Activity
Active year-round indoors, with peak mating and outdoor visibility occurring during late summer and autumn.
Description
The False Black Widow is a frequent indoor and outdoor dweller, often mistaken for its dangerous relative due to its dark, glossy appearance and bulbous abdomen. While harmless, it plays an effective role in regulating household insect populations.
Key Features
Glossy, bulbous dark abdomen, lack of a red hourglass marking, distinctive cobweb structure, and comb-footed appearance.
Similar Species
Latrodectus species (True Black Widows), which feature the distinctive red hourglass marking on the underside of the abdomen.
Life Cycle
Females produce spherical, brownish silk egg sacs containing dozens to hundreds of eggs. Spiderlings disperse via ballooning or crawling after hatching, undergoing multiple molts to reach maturity.
Ecological Importance
Acts as an effective natural pest controller in domestic and wild ecosystems, keeping insect populations in check.
Conservation Status
Not evaluated by the IUCN, highly adaptable, and thriving globally alongside human settlements.
Interesting Facts
Despite their ominous common name, they help control populations of true pests and are surprisingly long-lived, with some females surviving for several years.
Photography Tips
Use macro lenses with diffused lighting to capture the glossy texture of the abdomen without causing the spider to drop from its web.
Identified: 2026-09-22T22:11:14.342917