Cupboard Spider, False Black Widow, Dark Comb-Footed Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae. Key family characteristics include a rounded abdomen, comb-like setae on the fourth tarsus used for flinging silk over prey, and building irregular tangle webs.
Physical Description
The spider has a glossy, bulbous, globular abdomen and a relatively compact cephalothorax. The body texture is smooth and shiny, lacking dense hairs. Females are significantly larger and rounder than males, which have narrower abdomens and longer legs.
Size Estimate
Body length is typically around 6 to 10.5 mm for females and 4 to 6 mm for males. The total leg span can reach up to 20 to 30 mm. The specimen shown appears to be a typical adult or subadult.
Coloration & Markings
Base coloration ranges from deep purplish-brown to charcoal black or reddish-brown. Unlike true black widows, it lacks a red hourglass marking, though it may display faint, pale yellowish or grayish chevron patterns or spots on the dorsal abdomen.
Web Type
Builds an irregular, sticky tangle web commonly referred to as a cobweb. These webs are constructed in dark, sheltered locations such as corners, crevices, under furniture, inside cupboards, and around basements or garages.
Eye Arrangement
Features eight small eyes arranged in two horizontal rows of four, typical of the family Theridiidae, with the lateral eyes slightly touching or close together.
Leg Characteristics
Legs are long, slender, and generally unbanded, matching the body color or slightly lighter reddish-brown. They lack prominent spination but feature the specialized comb-like structures characteristic of cobweb spiders on the hind tarsi.
Venom & Safety Information
Venom Information
Possesses neurotoxic venom, but it is relatively mild compared to true widow spiders. The venom is primarily used to immobilize insect prey.
Medical Significance
Low medical significance. Bites are rare and usually occur only when the spider is accidentally trapped against human skin. Symptoms are generally minor, involving localized pain, redness, and swelling, occasionally accompanied by mild systemic effects like malaise or headache, but no necrosis.
Safety Recommendations
Avoid direct handling with bare hands. If found indoors, gently relocate the spider outdoors using a glass and a piece of paper. Keep living spaces clean and seal cracks to deter habitation.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution found worldwide in temperate regions. Commonly found indoors in human dwellings, garages, and sheds, as well as outdoors under rocks, logs, bark, and in dark crevices.
Behavior & Temperament
Docile and non-aggressive. They are nocturnal hunters that spend most of their time hanging upside down in their webs. When disturbed, they typically retreat to a nearby crack or curl up rather than bite.
Diet & Prey
Feeds primarily on crawling and flying insects, including woodlice, flies, mosquitoes, beetles, and other spiders. Prey is captured in the sticky web and subdued before feeding.
Seasonal Activity
Active year-round indoors, though outdoor populations show peak activity and mating during the warm summer and autumn months.
Description
Steatoda grossa, commonly known as the false black widow or cupboard spider, is a frequent indoor companion in temperate regions worldwide. Recognized by its glossy, bulbous body and deep brownish-red or purplish coloration, it constructs messy tangle webs in quiet corners and dark recesses. While sometimes mistaken for its more dangerous relatives, this spider is timid and serves as a natural pest controller against household insects.
Key Features
Glossy, globular abdomen, deep brownish-purple to black coloration, lack of a red hourglass marking, and construction of messy tangle webs in dark indoor corners.
Similar Species
Latrodectus species (True Black Widows), which possess a distinct red hourglass marking and more intense black coloration; Steatoda triangulosa (Triangle Spider), which features a distinct zigzag pattern on the abdomen.
Life Cycle
Females produce brownish-white silk egg sacs containing up to several hundred eggs, which are hidden within the web or nearby crevices. Spiderlings disperse via ballooning or crawling after hatching, maturing over several months. Lifespan for females can reach several years.
Ecological Importance
Acts as an effective natural predator of household pests, including nuisance insects and potential disease vectors, helping to regulate local invertebrate populations.
Conservation Status
Not evaluated by the IUCN, but secure, widespread, and highly adaptable to human-altered environments.
Interesting Facts
Despite being called a false black widow, Steatoda grossa has been known to successfully prey on true black widows when they invade its territory. They can also vibrate their webs rapidly when threatened to blur their image to potential predators.
Photography Tips
Use macro lenses with good side lighting to highlight the glossy texture and subtle dorsal markings. Photograph from a slight side or top angle while keeping a safe distance to avoid disturbing the spider.
Identified: 2026-10-02T13:52:09.423243