False Black Widow, Cupboard Spider, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae. Characterized by a globular abdomen and a comb of serrated bristles on the fourth leg tarsus.
Physical Description
A medium-sized spider with a very large, shiny, bulbous abdomen and a smaller cephalothorax. The surface is smooth and glossy, lacking the dense hairs found in wolf spiders. Femur and other leg segments are slender in proportion to the abdomen.
Size Estimate
Body length is approximately 6-11mm for females; leg span reaches 20-30mm. This specimen appears to be a mature female based on the large, rounded abdomen and dark coloration.
Coloration & Markings
Dark mahogany brown to purplish-black. Often features a pale, crescent-shaped band on the anterior portion of the abdomen and faint chevrons or spots, though these may fade to solid black in older individuals. It lacks the red hourglass of a true Black Widow.
Web Type
Tangle web or cobweb. It builds an irregular, three-dimensional scaffold of sticky silk, typically in dark corners, under furniture, or in crevices.
Eye Arrangement
Eight eyes arranged in two rows of four. The lateral eyes are typically contiguous (touching), which is a common feature of the Theridiidae family.
Leg Characteristics
Spindly and relatively long. The legs are generally the same dark brown or reddish-brown color as the body, sometimes slightly lighter at the joints. They lack heavy spines or distinctive banding.
Venom & Safety Information
Venom Information
Neurotoxic venom, but significantly less potent than true Latrodectus species. The venom contains alpha-latrotoxin but in lower concentrations or with less affinity for human receptors.
Medical Significance
Low to moderate significance. Bites are nicknamed 'Steatodism.' Symptoms include localized pain, swelling, and occasionally mild nausea or malaise. Symptoms usually resolve within 24-48 hours without medical intervention.
Safety Recommendations
Use gloves when cleaning out dark corners or moving stored boxes. If found, they can be easily relocated using a jar and a piece of paper. Most 'Black Widow' scares are actually misidentified False Widows.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found worldwide. Highly synanthropic, preferring man-made structures such as basements, crawl spaces, garages, and cupboards throughout North America, Europe, and Australasia.
Behavior & Temperament
Sedentary and nocturnal web-dwellers. They are non-aggressive and shy, typically retreating into a crevice when disturbed. They only bite if squeezed or pressed against skin.
Diet & Prey
Generalist predator feeding on woodlice, crickets, beetles, and even other spiders (including true Black Widows). They use sticky silk to wrap and immobilize prey before delivering a bite.
Seasonal Activity
Active year-round indoors due to controlled climates. Outdoors, they are most visible from late summer through autumn during the mating season.
Description
A glossy, dark spider common in household environments. Its resemblance to the Black Widow is striking, but it serves as a beneficial inhabitant by consuming indoor pests like roaches and ants. It is most often seen hanging upside down in its messy corner web.
Key Features
Glossy bulbous abdomen, dark brown/plum color, lack of red markings, and a pale crescent on the leading edge of the abdomen.
Similar Species
Latrodectus mactans (Northern Black Widow) which has a red hourglass; Steatoda borealis which is smaller and usually has a distinct light line down the center of the abdomen.
Life Cycle
Females produce several papery, round, off-white egg sacs. Spiderlings emerge and may balloon if outdoors. Lifespan for females can reach up to 6 years, which is quite long for a spider of this size.
Ecological Importance
Crucial for indoor pest control. They act as natural apex predators within the micro-ecosystems of basements and outbuildings, keeping insect populations in check.
Conservation Status
Not evaluated (IUCN), but populations are stable and widespread across the globe due to their adaptability to human habitation.
Interesting Facts
Steatoda spiders are known to displace true Black Widows in some urban environments. They are also famous for their longevity and can survive for months without food.
Photography Tips
Focus on the dorsal side to capture the pale crescent mark. Lighting is tricky due to their high-gloss finish; use diffused side-lighting to avoid a large white 'hot spot' or glare on the abdomen.
Identified: 2026-05-24T02:17:12.697594