False Black Widow, Cupboard Spider, Dark Comb-Footed Spider
Steatoda grossa
Family Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A robust spider with a bulbous, glossy abdomen shaped like a teardrop or grape. It has a significantly smaller cephalothorax (head region). Females are larger and more rounded, while males have smaller abdomens and longer legs.
Size Estimate
Adult female body length: 6-10 mm; total leg span: 15-25 mm. The specimen in the container appears to be a mature female.
Coloration & Markings
Deep purplish-brown to charcoal black base color. Typically features a pale, crescent-shaped band on the anterior portion of the abdomen and sometimes faint chevrons or dots. It lacks the bright red hourglass of a true Black Widow.
Web Type
Messy, three-dimensional tangle or cobweb. These are typically built in dark corners, under shelves, or in undisturbed indoor/outdoor structures.
Eye Arrangement
Eight eyes arranged in two rows of four. The anterior median eyes are usually the smallest and darkest, characteristic of the Theridiidae family.
Leg Characteristics
Slender but strong legs, often slightly lighter in color (reddish-brown) than the body. The fourth pair of legs has a row of serrated bristles used to comb silk onto prey.
Venom & Safety Information
Venom Information
Contains alphatoxin, which can cause symptoms similar to latrodectism (widow envenomation) but significantly milder and without long-term danger.
Medical Significance
Low to moderate clinical importance. Bites may cause localized pain, swelling, and occasionally nausea or lethargy. They are not considered life-threatening.
Safety Recommendations
Avoid handling with bare hands. If found indoors, they can be easily relocated using a cup and card. Wear gloves when cleaning out dark corners or woodpiles.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution found globally. Prefers dark, damp environments such as basements, crawl spaces, garages, and outdoor sheds or under stones.
Behavior & Temperament
Sedentary and non-aggressive. They spend most of their time hanging upside down in their web. They are known to play dead (thanatosis) when threatened.
Diet & Prey
Generalist predator feeding on woodlice, beetles, crickets, and other spiders. They use their sticky silk to entangle prey much larger than themselves.
Seasonal Activity
Active year-round in indoor environments. Peaks in visibility during autumn when males wander in search of mates.
Description
This glassy, dark spider is the famous 'False Widow.' While its appearance can be intimidating, it is a master of pest control that prefers to remain hidden in the dark nooks of human dwellings.
Key Features
Glossy bulbous abdomen, dark purplish-brown hue, lack of red hourglass, and specialized comb-foot on the fourth legs.
Similar Species
Latrodectus mactans (Black Widow) - distinguished by the red hourglass; Steatoda nobilis (Noble False Widow) - has more distinct 'skull' markings on the abdomen.
Life Cycle
Females produce round, papery, white egg sacs containing 40-100 eggs. They can live up to 6 years, which is unusually long for small spiders.
Ecological Importance
Highly effective at controlling household pests like roaches and woodlice. They serve as an important intermediary predator in urban ecosystems.
Conservation Status
Not evaluated by IUCN; however, they are a highly successful synanthropic species with stable and expanding populations.
Interesting Facts
They are known to prey upon true Black Widows, essentially acting as a natural competitor and control agent in shared habitats.
Photography Tips
Focus on the dorsal (top) side of the abdomen to capture the crescent marking. Use a side light to highlight the glossy texture and reflect the eye pattern.
Identified: 2026-07-20T01:53:58.159787