False Black Widow, Cupboard Spider, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A medium-sized spider with an bulbous, oval-shaped abdomen and a smaller cephalothorax. The surface is glossy and smooth, lacking the dense hairs found in many other families. Females have a larger, more rounded abdomen, while males (like the one pictured, suggested by the visible pedipalps) are slimmer with more pronounced appendages.
Size Estimate
Body length 6-10mm (females) or 4-6mm (males). Leg span typically reaches 15-25mm. This appears to be an adult male.
Coloration & Markings
Deep mahogany to purplish-black. It lacks the distinctive red hourglass of a true Black Widow. Juveniles and some adults may have a pale, crescent-shaped band on the anterior of the abdomen and light-colored spots or chevrons on the dorsal side.
Web Type
Tangle web or 'cobweb'. A messy, three-dimensional scaffold of sticky silk often built in corners, under furniture, or in cupboards.
Eye Arrangement
Eight eyes arranged in two rows of four. The eyes are small and typical of the Theridiidae family, oriented to detect vibrations in the web rather than for sharp visual hunting.
Leg Characteristics
Relatively long and slender legs, usually dark reddish-brown or black. The fourth pair of legs features a 'comb' of serrated bristles used to wrap prey in silk.
Venom & Safety Information
Venom Information
Neurotoxic venom similar in type to Latrodectus but significantly less potent. It is designed to immobilize small invertebrates and is not considered life-threatening to healthy humans.
Medical Significance
Low. While bites can cause 'steatodism' (localized pain, redness, and occasionally nausea or lethargy), symptoms are generally mild and self-limiting. Treatment is symptomatic (cold compress/pain relief). Seek medical attention only if allergic reactions occur.
Safety Recommendations
Relocate using the 'cup and card' method if found indoors. Wear gloves when cleaning dark areas like garages or woodpiles to avoid accidental defensive bites.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution worldwide. Frequently found indoors in dark, undisturbed areas like basements, crawlspaces, and garages. Outdoors, they inhabit crevices, stone walls, and hollow logs.
Behavior & Temperament
Sedentary and non-aggressive. They spend most of their time hanging upside down in their webs. When threatened, they typically retreat into a corner or drop to the floor rather than biting.
Diet & Prey
Generalist predators feeding on various insects, including flies, moths, ants, and even other spiders (including true Black Widows). They use sticky silk to entangle prey before delivering a paralyzing bite.
Seasonal Activity
Active year-round in indoor environments. Outdoors, peak activity occurs in late summer and autumn for mating.
Description
The False Black Widow is a common household resident often mistaken for its more dangerous look-alike. Characterized by a glossy, dark body and a penchant for dark corners, it is a master of the tangle web. Unlike the true widow, it lacks the bright red markings and has a more subdued, purplish-brown hue. It is an unobtrusive hunter that provides excellent pest control within human structures.
Key Features
Glossy mahogany/dark body; absence of red hourglass; bulbous abdomen; 'comb' on back legs; tangled cobweb architecture.
Similar Species
Latrodectus (True Black Widows) - 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 papery, cream-colored egg sacs over their lifespan. Spiderlings disperse via ballooning. Females can live for several years, while males typically have a shorter lifespan following maturity.
Ecological Importance
Significant urban pest controller. They consume high volumes of nuisance insects and help regulate populations of other spiders within human-modified environments.
Conservation Status
Not evaluated; common and widespread with stable populations.
Interesting Facts
Steatoda grossa is known to hunt and eat the more venomous Redback and Black Widow spiders, effectively acting as a natural competitor that can keep widow populations down in homes.
Photography Tips
Focus on the dorsal markings of the abdomen and the shape of the pedipalps for sex identification. Diffused lighting helps reduce the harsh glare on their glossy carapaces.
Identified: 2026-07-08T19:00:11.571565