False Black Widow, Cupboard Spider, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae. Characterized by a comb of serrated bristles on the tarsus of the fourth leg.
Physical Description
A bulbous, glossy spider. Females have a large, rounded abdomen while males are slimmer. The texture is smooth and waxy with a cephalothorax that is significantly smaller than the abdomen.
Size Estimate
Body length is typically 6-10 mm for females and 4-6 mm for males. Leg span can reach 20-25 mm. The specimen in the image appears to be an adult female.
Coloration & Markings
Deep purplish-brown to black base color. It frequently features a pale, crescent-shaped band on the front of the abdomen and a faint pattern of triangles or chevrons along the dorsal midline.
Web Type
Tangle web or 'cobweb'. It is a messy, three-dimensional scaffold of sticky silk often built in corners, crevices, or under objects.
Eye Arrangement
Eight eyes arranged in two rows. The lateral eyes are typically touching or very close, which is a hallmark of the Theridiidae family.
Leg Characteristics
Relatively long and slender compared to the body. They are typically the same dark color as the body, lacking conspicuous spines, and featuring the 'comb-foot' bristles for silk manipulation.
Venom & Safety Information
Venom Information
Contains latrodectine-like toxins, though much less potent than true widows. The venom is neurotoxic but generally not dangerous to healthy humans.
Medical Significance
Low medical significance. Bites may cause localized pain, swelling, and occasionally mild system symptoms like nausea or lethargy. Treatment is usually just local cleaning and ice; seek help if symptoms persist.
Safety Recommendations
If found, they can be safely relocated using a jar and a piece of paper. Wear gloves when cleaning dark, dusty areas like garages or woodpiles to avoid accidental defensive bites.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found worldwide. Prefers dark, sheltered areas like basements, garages, crawl spaces, and under outdoor furniture or grills.
Behavior & Temperament
Reclusive and non-aggressive. They prefer to stay hidden in crevices and will usually retreat or play dead (thanatosis) if disturbed. They are active primarily at night.
Diet & Prey
Generalist predators feeding on various insects, woodlice, and even other spiders (including true Widows). They use sticky silk to entangle and then bite their prey.
Seasonal Activity
Active year-round in indoor or sheltered environments, though mating and egg-laying typically peak in late summer and autumn.
Description
The Steatoda grossa is a common household resident often mistaken for a black widow. With its glossy, dark, chocolatey-brown body and penchant for dark corners, it is a master of pest control within the home.
Key Features
Glossy rounded abdomen, purplish-brown hue, lack of a red hourglass marking, and the presence of a pale crescent on the anterior abdomen.
Similar Species
Latrodectus species (True Black Widows), which have a red hourglass; and Steatoda nobilis (Noble False Widow), which typically has a 'skull' pattern on the abdomen.
Life Cycle
Females produce round, white-to-cream silk egg sacs. Spiderlings emerge and often balloon. Lifespan for females can be up to 6 years, while males live significantly shorter lives.
Ecological Importance
Significant role in controlling domestic pests such as flies, moths, and cockroaches. They serve as a natural, non-toxic form of pest management.
Conservation Status
Not evaluated by the IUCN, but populations are stable and widespread globally as a synanthropic species.
Interesting Facts
They are known to prey on more dangerous spiders, including the Black Widow. In some lab settings, they have been used to study the chemical properties of cobweb silk.
Photography Tips
Focus on the dorsal pattern of the abdomen and the side view to show body shape. Use a macro lens or high-brightness flashlight to reveal the subtle purple/brown tones in the dark exoskeleton.
Identified: 2026-07-20T01:55:33.430685