Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae. Characterized by high-domed abdomens and irregular tangle webs.
Physical Description
Small spider with a bulbous, teardrop-shaped abdomen that is significantly larger than the cephalothorax. The surface is covered in fine hairs, giving it a slightly matte appearance.
Size Estimate
Body length 5-8 mm for females; leg span approximately 15-25 mm. The large spheres shown are egg sacs, which are usually larger than the spider itself.
Coloration & Markings
Variable mottled patterns of tan, brown, and grey with darker chevron-like splotches on the abdomen. Pale tan legs often featuring darker banding at the joints.
Web Type
Tangle web or cobweb. An irregular, messy-looking maze of silk built in corners, under eaves, or between wall surfaces, often containing debris and multiple egg sacs.
Eye Arrangement
8 eyes in two rows of four. The eyes are small and typical of cobweb spiders, which rely more on web vibrations than vision for hunting.
Leg Characteristics
Long, slender legs with the first pair being the longest. They feature 'comb-feet' (serrated bristles) on the fourth tarsus to wrap prey in silk.
Venom & Safety Information
Venom Information
Neurotoxic venom specialized for small invertebrates. It is not considered dangerous or potent to humans.
Medical Significance
Low medical significance. Bites are rare and typically result only in localized redness, mild swelling, or itching, similar to a bee sting.
Safety Recommendations
Harmless to humans. If the web is unsightly, relocate the spider using a jar and paper to an outdoor shed or garden. No special first aid is usually required for bites.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution worldwide; extremely common in North America. Found primarily in and around human structures, sheds, garages, and basements.
Behavior & Temperament
Passive and reclusive. They spend most of their time hanging upside down in the web. They are not aggressive and usually drop or run away when disturbed.
Diet & Prey
Generalist predators eating flies, mosquitoes, ants, and occasionally other spiders. They use their long legs to fling sticky silk over prey to immobilize it.
Seasonal Activity
Active year-round in temperature-controlled indoor environments; peak outdoor activity and egg-laying occur in late summer and autumn.
Description
The quintessential 'cobweb maker' found in homes, this spider is a master of domestic pest control. While their webs look messy, they are highly effective traps for flying insects.
Key Features
Tan mottled bulbous abdomen, comb-like hairs on hind legs, and unique papery brown spherical/pear-shaped egg sacs kept in a messy tangle web.
Similar Species
Steatoda borealis (False Widow) which is darker/shinier, and the Brown Widow (Latrodectus geometricus) which has spiked egg sacs rather than smooth ones.
Life Cycle
Females produce distinctive papery, brown, pear-shaped or spherical egg sacs (visible in photo). A single female can produce up to 17 sacs in her lifetime, each containing hundreds of eggs.
Ecological Importance
Highly beneficial for pest control inside homes, naturally reducing populations of flies, gnats, and varied household pests without the use of chemicals.
Conservation Status
Not evaluated by IUCN; population is stable and extremely abundant due to adaptation to human environments.
Interesting Facts
Females and males sometimes share a web for long periods before mating. They are known to exhibit 'thanatosis' or playing dead if they feel threatened.
Photography Tips
Focus on the egg sacs for identification, as they are diagnostic. Use a macro lens or high-zoom setting to capture the mottled pattern on the abdomen and leg banding.
Identified: 2026-06-17T18:55:46.909276