False Black Widow, Cupboard Spider, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A medium-sized spider with a bulbous, glossy, teardrop-shaped abdomen and a smaller, oval cephalothorax. The surface is smooth and shiny, appearing almost leathery or wax-like. Females have a significantly larger and more rounded abdomen than males.
Size Estimate
Body length: 6-10 mm for females, 4-6 mm for males. Leg span typically reaches 15-25 mm. This specimen looks like an adult female.
Coloration & Markings
Deep purplish-brown to blackish base color. Typically features a pale, crescent-shaped band on the anterior portion of the abdomen. Some individuals show faint chevrons or spots on the dorsal side, though these fade with age. It lacks the red hourglass of a true Black Widow.
Web Type
Tangle web or cobweb. A messy, irregular structure of sticky silk often built in corners, under furniture, or in cupboards, usually with a tubular retreat where the spider hides.
Eye Arrangement
Eight eyes arranged in two rows. The eyes are small and typical of the Theridiidae family, though not easily visible without macro photography.
Leg Characteristics
Relatively long and slender compared to the body. Often reddish-brown or darker, matching the cephalothorax. They lack prominent spines but have a 'comb' of serrated bristles on the tarsus of the fourth leg for silk wrapping.
Venom & Safety Information
Venom Information
Contains latrodectine-like toxins, but much less potent than true widows. The venom is primarily used to immobilize small arthropods.
Medical Significance
Low danger level. Bites are rare and typically result in localized pain, redness, and minor swelling lasting for a few hours. Some may experience mild malaise or blisters, but symptoms usually resolve without medical intervention.
Safety Recommendations
Relocate using the 'cup and paper' method if found indoors. To prevent bites, wear gloves when cleaning dark corners or moving stored boxes. If bitten, clean the area with soap and water.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found worldwide. Highly synanthropic, preferring indoor environments like basements, garages, crawl spaces, and cupboards. Occasionally found outdoors under logs or stones.
Behavior & Temperament
Sedentary and nocturnal. They are very shy and docile, typically retreating into a corner or dropping from their web when disturbed. They are not aggressive toward humans and only bite if squeezed or trapped against skin.
Diet & Prey
Generalist predator feeding on woodlice, crickets, flies, and even other spiders (including true Black Widows). They use their 'comb-foot' to throw sticky silk over struggling prey.
Seasonal Activity
Active year-round in indoor environments due to stable temperatures. Mating and egg-laying peak in spring and summer.
Description
The False Black Widow is a master of the shadows, often mistaken for its more dangerous namesake. It is a glossy, dark-colored spider that lives a quiet life in the corners of homes, performing valuable pest control by catching wandering insects.
Key Features
Glossy bulbous abdomen, dark chocolate or purplish-brown color, pale crescent mark at the front of the abdomen, and lack of a red hourglass marking.
Similar Species
Latrodectus mactans (Black Widow) which has a red hourglass; Steatoda nobilis (Noble False Widow) which has 'skull' markings; Steatoda borealis which is smaller and more reddish-brown.
Life Cycle
Females produce round, white to cream-colored papery egg sacs containing 40-100 eggs. Spiderlings disperse via ballooning. Females can live up to 6 years; males typically live much shorter lives.
Ecological Importance
Crucial indoor pest controllers. They effectively reduce populations of cockroaches, flies, and woodlice in domestic settings, acting as natural 'exterminators.'
Conservation Status
Not evaluated by the IUCN; considered stable and widespread due to its adaptation to human dwellings.
Interesting Facts
In film and television, this species is frequently used as a 'stunt double' for Black Widows because they look similar but are safe for actors to handle. They are also known to hunt and eat the more venomous true Black Widows.
Photography Tips
Focus on the dorsal (top) side of the abdomen to capture the faint markings and the crescent. Use lateral lighting to highlight the glossy texture and avoid reflections from a direct flash.
Identified: 2026-05-25T16:23:30.379273