Common House Spider, American House Spider
Parasteatoda tepidariorum
Family Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A small spider with a large, bulbous, high-set abdomen that is often mottled. The cephalothorax is small and reddish-brown. The abdomen is notably teardrop-shaped when viewed from the side.
Size Estimate
The specimen in the photo appears to be a small juvenile or male, approximately 3-5mm in body length. Adult females can reach 6-8mm with a leg span of 20mm.
Coloration & Markings
Typically a mix of tan, brown, and grey with darker chevron-like patterns on the abdomen. Legs often show dark banding at the joints.
Web Type
Tangle web or cobweb. These are messy, non-symmetrical structures typically found in corners, under furniture, or near window frames.
Eye Arrangement
Like most Theridiids, they have eight eyes arranged in two rows of four, though they are difficult to see without high magnification.
Leg Characteristics
The legs are long and slender. The first pair of legs is significantly longer than the others, which is a characteristic trait of this family for silk manipulation.
Venom & Safety Information
Venom Information
Contains latrodectine-like neurotoxins used to paralyze insects, but the volume is negligible and the delivery system (chelicerae) is rarely large enough to pierce human skin.
Medical Significance
Harmless to humans. Bites are extremely rare and usually result in only minor localized redness or itching similar to a mosquito bite.
Safety Recommendations
No action is required for safety. If relocation is desired, use a cup and a piece of paper to gently move the spider outside. They are beneficial to have in garages and basements.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found worldwide. Highly associated with human dwellings, sheds, garages, and vegetation near structures.
Behavior & Temperament
Very timid and non-aggressive. They spend most of their time hanging upside down in the center of their cobweb waiting for prey vibrations. If disturbed, they usually drop to the floor or retreat.
Diet & Prey
Generalist predators consuming flies, mosquitoes, ants, and even other spiders. They use sticky 'gum-foot' silken lines to snag crawling insects.
Seasonal Activity
Active year-round in climate-controlled indoor environments, though population peaks are often observed in late summer and autumn.
Description
The Common House Spider is the most frequent uninvited guest in homes worldwide. Its signature high-domed abdomen and tangled webs make it easy to spot in the corners of ceilings. While often maligned for creating 'cobwebs,' they are master insect hunters that stay strictly within their webs.
Key Features
Tangled cobweb habitat, bulbous teardrop-shaped abdomen, and long, thin, banded legs. Usually found upside down.
Similar Species
Often confused with the Brown Widow (Latrodectus geometricus), but the House Spider lacks the distinct orange hourglass and has a much more mottled, less geometric pattern.
Life Cycle
Females produce distinctive pear-shaped, tan/brown papery egg sacs. A single female can produce several sacs in a season, each containing hundreds of eggs. Lifespan is approximately one year.
Ecological Importance
Primary domestic pest controller. They eat massive quantities of household pests like fruit flies, gnats, and flies, providing a free and natural pest management service.
Conservation Status
Not evaluated (IUCN), but extremely common and widespread with no known threats to population stability.
Interesting Facts
Despite their small size, they can catch prey much larger than themselves, including crickets and occasionally small lizards, by using their specialized comb-feet to wrap the prey in silk from a distance.
Photography Tips
Focus on the side profile to capture the distinct abdomen shape. Use a macro lens or 'portrait' setting to help the camera focus on the thin silk of the web.
Identified: 2026-06-15T15:14:58.289120