False Widow, Cupboard Spider, Dark Comb-footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A bulbous, glossy abdomen dominates the silhouette, typical of the Theridiidae family. The cephalothorax is smaller and darker, often with a somewhat flattened profile compared to the high-domed abdomen.
Size Estimate
Body length 6-10mm for females; leg span approximately 20-30mm. This specimen appears to be an adult female.
Coloration & Markings
Dark purple-brown to blackish base color. The abdomen features a pale, crescent-shaped band at the front and a series of triangular or chevron-like pale splotches along the midline.
Web Type
Irregular tangle web or 'cobweb' with sticky 'gumfoot' lines extending to the substrate; usually built in dark corners or crevices.
Eye Arrangement
Eight eyes arranged in two rows of four, with the lateral eyes almost touching, creating a clustered appearance typical of cobweb spiders.
Leg Characteristics
Relatively slender but robust legs; darker reddish-brown or dark mahogany, sometimes showing faint banding or darker segments near the joints.
Venom & Safety Information
Venom Information
Contains latrodectine-like toxins but significantly less potent than true widows. Small amounts of neurotoxic venom used to paralyze insect prey.
Medical Significance
Low medical significance. Bites are rare and usually result in localized pain, redness, and minor swelling. Symptoms typically resolve within 24-48 hours without treatment.
Safety Recommendations
If relocation is needed, use the 'cup and card' method. Wear gloves when cleaning dark, undisturbed areas like garages or basements where they may hide.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; extremely common in Europe, North America, and Australasia. Lives inside homes (cupboards, basements) and outdoors in sheds or under logs.
Behavior & Temperament
Sedentary, nocturnal, and very reclusive. They are non-aggressive and prefer to retreat or play dead (thanatosis) when disturbed rather than bite.
Diet & Prey
Generalist predator feeding on woodlice, beetles, flies, and even other spiders (including 'true' black widows). They use sticky silk to entangle prey.
Seasonal Activity
Active year-round in temperature-controlled indoor environments; peak outdoor activity and mating occur in late summer and autumn.
Description
Steatoda grossa is a sophisticated urban dweller, often mistaken for more dangerous cousins. With its sleek, dark, 'plum-like' abdomen and messy web work, it is a master of corners and crevices.
Key Features
Glossy, dark bulbous abdomen with a pale anterior crescent band and absence of a red hourglass marking on the underside.
Similar Species
Latrodectus species (Black Widows), which have a red hourglass; and Steatoda nobilis (Noble False Widow), which typically has 'skull-shaped' abdominal markings.
Life Cycle
Females produce round, papery, white egg sacs containing 40-100 eggs. They are long-lived for spiders, with females surviving up to 6 years in stable indoor environments.
Ecological Importance
Highly effective indoor pest control, predating on nuisance insects like cockroaches, flies, and woodlice that enter human structures.
Conservation Status
Not evaluated by the IUCN; widespread and common with stable populations worldwide.
Interesting Facts
They are known to hunt and eat Redback or Black Widow spiders, effectively acting as a natural competitor and control for more venomous species.
Photography Tips
Focus on the dorsal abdominal pattern and the glossy texture. A lateral shot helps show the cephalothorax shape and the absence of ventral red markings.
Identified: 2026-06-26T02:14:13.897648