Cupboard Spider, False Black Widow, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
The spider has a bulbous, glossy, globular abdomen and a smaller, oval cephalothorax. The body appears smooth and shiny with a somewhat leathery texture on the abdomen. Proportions lean heavily toward a large, rounded abdomen relative to the cephalothorax and legs.
Size Estimate
Body length approximately 6 to 10 millimeters for females, with a leg span around 15 to 20 millimeters. The specimen appears small, likely a juvenile or a smaller adult male.
Coloration & Markings
Deep purplish-brown to blackish base coloration, often featuring subtle pale yellowish or whitish markings, sometimes forming faint chevron patterns or a crescent shape across the dorsal abdomen.
Web Type
Tangle web or irregular cobweb constructed in dark, undisturbed corners, crevices, or near ground level indoors and outdoors.
Eye Arrangement
Eight small eyes arranged in two rows of four, typical of the Theridiidae family, positioned on the front of the carapace.
Leg Characteristics
Thin, moderately long legs with subtle banding or dark coloration matching the body, lacking heavy spination but equipped with a comb of serrated bristles on the fourth tarsus characteristic of theridiids.
Venom & Safety Information
Venom Information
Contains neurotoxic components typical of cobweb spiders, but the venom is relatively mild and not life-threatening to humans.
Medical Significance
Not considered medically significant. A bite can cause minor local pain, redness, and swelling, occasionally accompanied by mild systemic symptoms like malaise, but severe reactions are extremely rare.
Safety Recommendations
Avoid direct handling with bare hands; if found indoors, gently relocate using a container and piece of card. Bites are rare and easily prevented by wearing gloves when cleaning dark, undisturbed spaces.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; frequently found in temperate regions worldwide, inhabiting human dwellings, outbuildings, basements, and dark crevices outdoors under rocks and bark.
Behavior & Temperament
Docile and non-aggressive; typically retreats or curls up when disturbed rather than biting, preferring to remain hidden in its web.
Diet & Prey
Feeds primarily on crawling and flying insects trapped in its sticky web, including ants, beetles, woodlice, and occasionally other spiders.
Seasonal Activity
Active year-round indoors, with peak visibility and mating occurring during the warmer summer and autumn months.
Description
The Cupboard Spider is a common and inconspicuous inhabitant of human habitations. Often mistaken for true black widows due to its dark, bulbous silhouette, it is a harmless and beneficial predator that helps keep household pest populations under control.
Key Features
Glossy, bulbous, dark-colored abdomen; lack of a red hourglass marking; irregular cobweb construction; presence of a comb-like row of setae on the hind tarsi.
Similar Species
Latrodectus species (Black Widows), which feature the distinct red hourglass marking on the underside of the abdomen and lack the subtle pale markings or purplish-brown tone of Steatoda grossa.
Life Cycle
Females produce brownish silk egg sacs containing dozens to hundreds of eggs. Spiderlings disperse via ballooning or crawling after hatching, undergoing multiple molts to reach maturity over a year.
Ecological Importance
Acts as a natural pest control agent by preying on household insects and other arthropods within human structures and natural microhabitats.
Conservation Status
Not evaluated by the IUCN, but populations are secure, abundant, and widely distributed globally.
Interesting Facts
Despite being called the False Black Widow, Steatoda species can sometimes prey on true black widows by invading their webs and subduing them.
Photography Tips
Use macro lenses with adequate lighting to capture dorsal markings and eye arrangements. Maintain a safe distance and photograph against a neutral background for clarity.
Identified: 2026-10-06T13:54:22.515349