Cupboard Spider, False Black Widow, Dark Cobweb Spider
Steatoda grossa
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
The cup-shaped abdomen is bulbous, plump, and glossy, paired with a smaller, darker cephalothorax. The overall texture is smooth yet robust, typical of cobweb weavers.
Size Estimate
Body length ranges from 6 to 10.5 mm for females, making this likely an adult female specimen.
Coloration & Markings
Deep brownish-purple to black base coloration with pale yellowish or pinkish-white geometric markings, often forming chevron or crescent patterns across the dorsal abdomen.
Web Type
A messy, irregular tangle web or cobweb constructed in dark, protected corners near the ground or in structural crevices.
Eye Arrangement
Eight small eyes arranged in two slightly curved horizontal rows of four, typical of the family Theridiidae.
Leg Characteristics
Thin, moderately long legs featuring subtle dark banding, lacking heavy spination but equipped with a comb of serrated bristles on the fourth tarsus.
Venom & Safety Information
Venom Information
Contains neurotoxic components (latrotoxin-like), but potency is significantly milder than true widow spiders.
Medical Significance
Minimally dangerous to humans. Bites are rare and usually result in mild localized pain, swelling, and occasionally systemic symptoms similar to a mild bee sting.
Safety Recommendations
Avoid direct handling with bare hands; if relocation is necessary, gently guide the spider into a container using a piece of paper.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution globally; found in dark, sheltered areas around human habitations, including basements, sheds, crawlspaces, and under furniture.
Behavior & Temperament
Reclusive, nocturnal, and non-aggressive. It hangs upside down in its web and retreats rapidly when disturbed.
Diet & Prey
Feeds on crawling insects, woodlice, and other spiders, sometimes successfully subduing much larger prey including other medically significant species.
Seasonal Activity
Active year-round indoors, with peak visibility and mating activity during late summer and autumn.
Description
Often mistaken for the true black widow due to its dark coloration and bulbous abdomen, the false black widow is a harmless and beneficial resident of dark corners.
Key Features
Glossy, bulbous abdomen with pale geometric markings, absence of a red hourglass shape, and a messy cobweb structure.
Similar Species
Latrodectus species (Black Widows), which lack the distinct light-colored dorsal chevrons and possess a red hourglass marking.
Life Cycle
Females produce brownish silk egg sacs containing up to several hundred eggs, guarding them within the web until spiderlings hatch and disperse.
Ecological Importance
Acts as an effective natural pest controller by managing populations of household insects and occasional invading arachnids.
Conservation Status
Not evaluated by the IUCN, but highly secure and widespread globally as a synanthropic species.
Interesting Facts
Known to occasionally prey on true black widows by invading their webs and wrapping them from a distance.
Photography Tips
Use macro lighting and a stable tripod to capture the fine geometric patterns on the dorsal abdomen while maintaining a safe distance.
Identified: 2026-09-24T00:13:17.735853