False Black Widow, Cupboard Spider, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A robust, bulbous-bodied spider with a large, shiny, globe-like abdomen and a smaller cephalothorax. The surface is smooth and glossy, lacking the dense fuzzy hair found in wolf spiders. Females have the characteristic 'widow' shape with thick, arched abdomens, while males are thinner and more elongated.
Size Estimate
Estimated body length 6-10mm (adult female). Total leg span typically 15-25mm. This appears to be an adult specimen.
Coloration & Markings
Dark purple-brown to nearly black base coloration. The abdomen feature a crescents-shaped pale band on the anterior end and a series of pale, often triangular or chevron-like spots down the center which fade with age. Unlike the True Black Widow, it lacks a red hourglass.
Web Type
Tangle web or 'cobweb'. It creates an irregular, three-dimensional maze of sticky silk, typically in dark corners, cupboards, or under furniture.
Eye Arrangement
Eight eyes arranged in two rows. The lateral eyes are situated close to each other. Characteristic of Theridiidae, the eyes are relatively small and the spider relies more on vibration than sight.
Leg Characteristics
Tapered legs that are typically the same color as the body or slightly lighter brown. They lack prominent 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 latrodectine-like toxins but is much less potent than True Black Widow venom. It is primarily neurotoxic to small prey but lacks the high concentration of toxins dangerous to humans.
Medical Significance
Low to moderate medical significance. Bites can cause localized pain, swelling, and occasionally mild system symptoms like nausea or lethargy (steatodism), but symptoms typically resolve within 1-2 days without medical intervention.
Safety Recommendations
If found indoors, they can be easily relocated using the 'cup and paper' method. Wear gloves when cleaning out dark, neglected areas like garages or basements to avoid accidental bites.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found worldwide. Highly synanthropic, preferring indoor environments like basements, garages, cupboards, and crevices in walls, as well as outdoor sheltered spots like under rocks or woodpiles.
Behavior & Temperament
Sedentary and nocturnal. They are very shy and reclusive, typically retreating to a crevice when disturbed. They are not aggressive and usually only bite if pinched or squeezed against skin.
Diet & Prey
Generalist predator of crawling insects and other spiders. They are known to successfully hunt and eat other 'house' spiders, including True Black Widows and cellar spiders.
Seasonal Activity
Active year-round in indoor environments, though sightings may increase in autumn as males wander in search of mates.
Description
The False Black Widow is a master of the shadows, often living undetected in human homes for years. Its glossy, darkened abdomen gives it an intimidating appearance, but it serves as an excellent natural pest controller, removing unwanted insects and even more venomous spiders from its territory.
Key Features
Glossy bulbous abdomen, dark brown/purple-black color, pale crescent mark on the front of the abdomen, absence of a red hourglass marking, and irregular tangle web.
Similar Species
Latrodectus species (True Black Widows), which have a red hourglass; Steatoda nobilis (Noble False Widow), which has a more distinct 'skull' pattern on the abdomen.
Life Cycle
Females produce round, white to cream-colored papery egg sacs throughout the year. Spiderlings emerge after about a month. Females are long-lived, often surviving up to 6 years, while males live much shorter lives.
Ecological Importance
Provides significant natural pest control within human structures, preying on ants, flies, beetles, and even cockroaches.
Conservation Status
Not evaluated by the IUCN; however, they are a stable and common species globally with no known threats.
Interesting Facts
Steatoda grossa is often mistaken for the Black Widow in film and television; they are frequently used as 'stunt doubles' because they look similar but are much safer for actors to handle.
Photography Tips
Focus on the dorsal (top) pattern of the abdomen and use a flash to highlight the glossy texture and crescent markings. A side profile helps show the bulbous shape vs. the cephalothorax.
Identified: 2026-06-26T02:12:24.215118