False Black Widow, Cupboard Spider, Dark Comb-Footed Spider
Steatoda grossa
Family Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
The spider has a glossy, bulbous, pear-shaped abdomen and a smaller cephalothorax. The exoskeleton appears smooth and shiny, lacking the dense hairs found on wolf spiders. Females have a significantly larger, more rounded abdomen compared to the slimmer, smaller males.
Size Estimate
Body length 6-10 mm for females, 4-6 mm for males. Leg span typically ranges from 15-25 mm. This specimen appears to be an adult female based on abdomen proportions.
Coloration & Markings
Dark purple-brown to nearly black base color. It lacks the bright red hourglass of a true Black Widow. Often features a pale, crescent-shaped band on the anterior of the abdomen and sometimes faint light spots or chevrons dorsally.
Web Type
Tangle web or cobweb. It builds an irregular, three-dimensional maze of sticky silk, typically in dark corners or crevices.
Eye Arrangement
Eight eyes arranged in two rows of four. The lateral eyes are often touching or very close together, typical of the Theridiidae family.
Leg Characteristics
Slender, dark legs proportional to the body. They lack heavy spines but have a 'comb' of serrated bristles on the tarsus of the fourth leg used to wrap prey in silk.
Venom & Safety Information
Venom Information
Contains latrodectism-like toxins but at much lower potency than Latrodectus. It is not considered life-threatening to healthy humans.
Medical Significance
Low to moderate significance. Bites may cause localized pain, blistering, or minor malaise (Steatodism), but symptoms are usually self-limiting. Seek medical attention if an allergic reaction occurs.
Safety Recommendations
Relocate using a jar and stiff paper if found in high-traffic areas. Wear gloves when cleaning dark corners or moving stored boxes to avoid accidental defensive bites.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found globally in temperate regions. Prefers dark, undisturbed areas like cupboards, basements, crawl spaces, and behind furniture.
Behavior & Temperament
Sedentary and nocturnal. It is a timid, non-aggressive spider that prefers to retreat into a crevice when disturbed rather than bite.
Diet & Prey
Generalist predator of crawling and flying insects, including pillbugs, beetles, and even other spiders (sometimes including true Black Widows).
Seasonal Activity
Active year-round in temperature-controlled indoor environments, with peak mating and egg production in summer and autumn.
Description
A common household resident, the False Black Widow is frequently mistaken for its more dangerous namesake. It is a masterful architect of messy-looking but highly effective silk snares that help keep indoor pest populations in check.
Key Features
Glossy chocolate-brown body, bulbous abdomen, lack of red hourglass, and irregular tangle web.
Similar Species
Latrodectus mactans (Black Widow) - distinguished by the red hourglass; Steatoda nobilis (Noble False Widow) - distinguished by a more distinct 'skull' pattern on the abdomen.
Life Cycle
Females produce several white to cream-colored papery egg sacs. Spiderlings disperse via ballooning. Adults can live up to 6 years in stable indoor environments.
Ecological Importance
Acts as a natural pest controller in domestic settings, consuming cockroaches, flies, and woodlice.
Conservation Status
Not evaluated by IUCN; stable and widespread due to its adaptation to human dwellings.
Interesting Facts
The venom is being studied for its ability to affect the nervous system of prey, and this species is known to actively hunt and displace more venomous spiders from its territory.
Photography Tips
Focus on the dorsal abdomen to capture the crescent marking; use a diffuse flash to show the glossy texture without overexposing the highlights.
Identified: 2026-06-24T23:30:42.908857