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 for manipulating silk, and building irregular tangle webs.
Physical Description
The spider has a glossy, bulbous, egg-shaped abdomen that overhangs the cephalothorax, typical of cobweb spiders. The body texture appears smooth and shiny with dark brown to purplish-black coloration. Females are considerably larger and rounder than males, while males are slimmer with longer legs.
Size Estimate
Body length ranges from 6 to 10.5 mm for females and 4 to 6 mm for males, with a leg span of roughly 2 to 3 cm. This appears to be an adult specimen based on the well-developed, rounded abdominal proportions.
Coloration & Markings
Deep brownish-purple, dark brown, or nearly black body. Some specimens display subtle lighter pale yellowish or greyish markings, chevron patterns, or crescent shapes on the dorsal abdomen, though older adults often appear uniformly dark.
Web Type
Builds an irregular, messy tangle web, commonly known as a cobweb, constructed in dark, sheltered areas such as corners, crevices, under furniture, or around doorframes and window sills.
Eye Arrangement
Eight small eyes arranged in two horizontal rows of four, typical of the Theridiidae family, with lateral eyes often touching or closely grouped.
Leg Characteristics
Long, slender legs with distinct dark banding on a lighter brown or yellowish base. The legs lack prominent spines but feature specialized comb structures on the hind tarsi for wrapping prey.
Venom & Safety Information
Venom Information
Possesses neurotoxic venom (latrotoxin-like compounds), but it is significantly less potent than that of true widow spiders. Envenomation causes mild to moderate local pain and swelling.
Medical Significance
Minimally dangerous to humans. Bites are rare and result in localized pain, redness, and occasionally mild systemic symptoms like malaise or headache (steatodism). Medical attention is rarely needed unless an allergic reaction occurs.
Safety Recommendations
Wear gloves when clearing out dark, undisturbed storage areas or cleaning window frames. If found indoors, it can be easily relocated outside using a container and a piece of card.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution, found globally in temperate regions, frequently associated with human habitation, building exteriors, basements, garages, and outbuildings, preferring dark, humid microhabitats.
Behavior & Temperament
Timid and non-aggressive, usually hanging upside down in its web. It retreats or plays dead when disturbed, only biting if trapped tightly against human skin.
Diet & Prey
Feeds on a variety of crawling and flying insects, including woodlice, flies, mosquitoes, beetles, and other spiders. Uses sticky silk threads to hoist and immobilize prey before delivering venom.
Seasonal Activity
Active year-round indoors, but most commonly noticed outdoors and around building exteriors during late summer and autumn during the peak mating season.
Description
Steatoda grossa, commonly known as the cupboard spider or false black widow, is a frequent dweller around human structures. With its glossy, bulbous abdomen and dark, rich coloration, it is often mistaken for its more dangerous relative, the black widow. However, it is a shy, beneficial predator that quietly helps control household insect populations from the safety of its messy corner web.
Key Features
Glossy bulbous abdomen, lack of a red hourglass marking (distinguishing it from true widows), dark purple-brown coloration, and construction of an irregular cobweb in a sheltered corner.
Similar Species
Latrodectus species (True Black Widows), which feature the characteristic red hourglass on the underside of the abdomen. Other Steatoda species like Steatoda triangulosa, which has distinct triangular patterns.
Life Cycle
Females produce spherical, brownish silk egg sacs containing up to several hundred eggs. Spiderlings hatch after a few weeks, disperse via ballooning or crawling, and mature over several months, with females living up to six years.
Ecological Importance
Acts as an effective natural pest controller in domestic and peridomestic environments, keeping populations of nuisance and disease-vector insects in check.
Conservation Status
Not evaluated by the IUCN, but secure, highly adaptable, and thriving globally alongside human development as a synanthropic species.
Interesting Facts
Despite being called the false black widow, Steatoda grossa can occasionally prey on true black widows by invading their webs and subduing them using superior silk-wrapping techniques.
Photography Tips
Use macro photography with side lighting to capture the glossy texture and subtle dorsal markings. Maintain a safe distance and photograph from above or the side while the spider is resting in its web.
Identified: 2026-10-06T20:56:52.497606