Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae. Characterized by building tangled, messy webs and possessing a comb-like row of bristles on their hind legs.
Physical Description
A small spider with a bulbous, teardrop-shaped abdomen that is significantly larger than the cephalothorax. The abdomen is often high and somewhat pointed at the rear. The surface is covered in fine hairs.
Size Estimate
Females reach 5-8 mm in body length; males are smaller at 3-5 mm. Leg span typically ranges from 15-25 mm. This specimen appears to be an adult female based on the large, rounded abdomen.
Coloration & Markings
Highly variable mottled patterns of tan, brown, and grey with darker chevron-like markings or spots. Often features a white spot at the highest point of the abdomen and dark bands on the legs.
Web Type
Tangle web or cobweb. A messy, non-symmetrical structure of sticky silk often built in corners, window frames, or under eaves. This specific web shows significant accumulation of dust and debris.
Eye Arrangement
Eight eyes arranged in two rows of four. The eyes are small and typically not the primary identification feature without high magnification.
Leg Characteristics
Long, slender legs with the first pair being the longest. They feature distinct dark banding/rings at the joints and have a specialized 'comb' of hairs on the fourth pair of legs for flinging silk over prey.
Venom & Safety Information
Venom Information
Neurotoxic venom used to paralyze small insects. The venom is very weak relative to humans and is not considered a medical threat.
Medical Significance
Negligible danger. Bites are rare and typically only happen if the spider is squeezed. Symptoms are usually limited to mild local swelling, redness, and itching, similar to a bee sting.
Safety Recommendations
Harmless; no action is usually required. If removal is desired, they can be easily relocated using a cup and a piece of paper. Wear gloves when cleaning out old webs to avoid rare defensive nips.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found worldwide. Most common in and around human structures, including basements, sheds, garages, and window frames, as well as under rocks and logs in nature.
Behavior & Temperament
Passive, sedentary hunters that wait in the web. They are extremely shy and will usually retreat or drop from the web if disturbed. They show almost no aggression toward humans.
Diet & Prey
Generalist predators consuming flies, mosquitoes, ants, and other spiders. In the image, the spider is seen feeding on a large insect (possibly a moth or grasshopper) that has become entangled.
Seasonal Activity
Active year-round in temperature-controlled indoor environments. Outdoors, they are most visible from late spring through autumn, with mating peaks in late summer.
Description
This ubiquitous neighbor is the quintessential 'cobweb spider.' Often overlooked, they are master architects of three-dimensional snares that provide excellent free pest control for homeowners. Their mottled brown patterns provide perfect camouflage against weathered wood and stone.
Key Features
Large bulbous abdomen, mottled brown/tan pattern, long banded legs, and the characteristic messy tangle web with teardrop-shaped egg sacs (when present).
Similar Species
Steatoda species (False Widows), which have a glossier, more oval abdomen, and Latrodectus (Widow spiders), which are usually solid black and have a red hourglass.
Life Cycle
Females produce several pear-shaped, papery brown egg sacs throughout the season. Spiderlings emerge and disperse via ballooning. They can live for a year or more in sheltered environments.
Ecological Importance
Critical urban predator that helps regulate populations of household pests like flies, gnats, and cockroaches. They serve as a food source for mud dauber wasps and larger spiders.
Conservation Status
Not evaluated by IUCN; they are extremely common and widespread with stable populations due to their adaptation to human environments.
Interesting Facts
Despite their small size, they can tackle prey many times their own weight by using their hind legs to throw 'sticky foot' silk lines from a distance, tethering the struggling insect to the web.
Photography Tips
Focus on the pattern on the top of the abdomen and the banding on the legs. Use a macro lens or 'Portrait' mode to blur the messy background of the web for better clarity of the spider itself.
Identified: 2026-05-16T14:55:11.708075