Cupboard Spider, False Black Widow, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae. Key family characteristics include a rounded, bulbous abdomen, comb-like setae on the fourth tarsus used to pull silk over prey, and the construction of irregular tangle webs.
Physical Description
The spider features a glossy, bulbous, globe-shaped abdomen that overhangs the cephalothorax slightly. The cephalothorax is oval-shaped and compact. Its overall texture is smooth and shiny rather than hairy, giving it a somewhat metallic or satin appearance.
Size Estimate
Body length typically ranges from 6 to 10.5 mm for females (males are slightly smaller at 4 to 6 mm), with a leg span of approximately 20 to 25 mm. The specimen in the image appears to be a sub-adult or adult female of moderate size.
Coloration & Markings
Deep purplish-brown to glossy black base coloration. Some specimens exhibit subtle lighter pale or yellowish markings, such as a crescent or band across the front of the abdomen or faint chevron patterns, though many appear uniformly dark.
Web Type
Irregular tangle web, often referred to as a cobweb. Constructed in dark, sheltered areas close to the ground or within structural cavities, consisting of sticky, haphazardly arranged silk threads designed to trip walking insects.
Eye Arrangement
Eight small eyes arranged in two distinct rows of four, typical of the family Theridiidae, with the lateral eyes slightly touching or closely grouped.
Leg Characteristics
Legs are moderately long, slender, and tapering, featuring subtle darker banding or rings. They lack heavy spines or specialized large adaptations, though they possess the characteristic comb-like serrated bristles on the hind tarsi for wrapping prey.
Venom & Safety Information
Venom Information
Neurotoxic venom containing latrotoxin-like compounds, though significantly milder than that of true widow spiders. Potency relative to humans is low to moderate.
Medical Significance
Not considered medically significant. A bite can cause mild localized pain, redness, and swelling, occasionally accompanied by mild systemic symptoms like malaise, but severe complications are extremely rare.
Safety Recommendations
Avoid handling with bare hands; wear gloves when cleaning dark, undisturbed storage areas. If found indoors, gently relocate using a cup and card rather than exterminating.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution, frequently found globally in temperate regions. Prefers dark, humid, and sheltered microhabitats such as basements, crawlspaces, under furniture, inside hollow logs, and around dark corners of buildings.
Behavior & Temperament
Non-aggressive and very timid. It spends most of its time motionless in its web. It relies on retreat or playing dead when disturbed, biting only as an absolute last resort if trapped directly against human skin.
Diet & Prey
Generalist predator feeding on crawling insects, woodlice, cockroaches, and occasionally other spiders. It uses sticky web threads to entangle prey before wrapping it securely and delivering venom.
Seasonal Activity
Active year-round indoors, with peak visibility and mating activity occurring during late summer and autumn as adults mature and search for sheltered winter sites.
Description
The cupboard spider is a common yet often misunderstood synanthropic arachnid. With its glossy, dark, rounded silhouette, it is frequently mistaken for its more dangerous relative, the black widow. However, it is a peaceful resident of dark corners, playing a beneficial role by keeping household insect populations in check without posing a serious threat to humans.
Key Features
Glossy, bulbous, dark brown to black abdomen; lack of a red hourglass marking; delicate slender legs with faint banding; preference for constructing tangled cobwebs in sheltered, indoor or subterranean spaces.
Similar Species
True Black Widow (Latrodectus spp.), which features a distinct red hourglass or bright spots and lacks the purplish-brown glossy tones; Steatoda triangulosa, which has a distinct triangular patterned back.
Life Cycle
Females produce spherical, brownish silk egg sacs containing up to several hundred eggs. Spiderlings disperse via ballooning or crawling. Molting occurs multiple times throughout growth; females can live for several years.
Ecological Importance
Acts as an effective natural pest controller in domestic and semi-natural environments, regulating populations of crawling insects and other arthropods.
Conservation Status
Not evaluated by the IUCN, but populations are secure, abundant, and widely distributed globally due to high adaptability to human environments.
Interesting Facts
Despite being called the 'false black widow,' Steatoda grossa occasionally preys on true black widows by invading their webs and subduing them using superior silk-wrapping techniques.
Photography Tips
Use macro lenses with a ring light or diffused external flash to highlight the glossy texture of the abdomen without causing harsh reflections. Shoot from a side angle to capture leg proportions and cephalothorax details clearly.
Identified: 2026-09-04T03:26:24.845369