Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A teardrop-shaped or bulbous abdomen that is significantly larger than the cephalothorax. The body is relatively smooth with fine hairs visible under magnification. Females have high, rounded abdomens while males are smaller with more slender bodies.
Size Estimate
Female body length typically 5–8 mm (0.2–0.3 in); Males 3–5 mm. Leg span including legs can reach up to 25 mm (1 inch). The specimen in the image appears to be an adult female.
Coloration & Markings
Generally a mottled tan, brown, or grey with dark patches. The abdomen often features a series of dark chevrons or 'V' shapes pointing toward the rear, and often has a small light spot at the very tip.
Web Type
Tangle web or cobweb. These are messy, irregular Three-dimensional structures built in corners, often with a central retreat where the spider hides.
Eye Arrangement
Eight eyes total, arranged in two rows of four. The lateral eyes are typically touching or very close to one another, which is a hallmark of the Theridiidae family.
Leg Characteristics
Long, thin legs, often with dark banding at the joints. The fourth pair of legs has a 'comb' of serrated bristles used to throw silk over prey, a defining feature of 'comb-footed' spiders.
Venom & Safety Information
Venom Information
The venom is a mild neurotoxin designed to paralyze small insects. It is not considered medically significant to humans.
Medical Significance
Harmless. Bites are extremely rare and typically only happen if the spider is squeezed. Symptoms are usually limited to localized redness, slight swelling, or itching, similar to a bee sting.
Safety Recommendations
No special precautions needed. If relocation is desired, use a cup and paper to move the spider outside or to a garage. They are beneficial to have around homes for free pest control.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found throughout the world. Primarily associated with human structures, preferring corners of rooms, basements, sheds, and under eaves.
Behavior & Temperament
Passive and reclusive. They are accidental 'interior designers,' frequently abandoning old webs to build new ones. They are non-aggressive and will usually drop on a silk line or retreat when disturbed.
Diet & Prey
Opportunistic hunters. Their diet consists of common household pests such as flies, mosquitoes, ants, and occasionally other small spiders. They use sticky 'gumfooted' lines to snag crawling insects.
Seasonal Activity
Active year-round in temperature-controlled indoor environments, though activity may peak in late summer and autumn in outdoor structures.
Description
The quintessential 'cobweb spider' found in homes globally. This spider is a master of the messy web and a quiet neighbor that provides excellent natural pest control. While often unnoticed, they are fascinating architects of complex 3D silk traps.
Key Features
Bulbous abdomen, mottled brown coloration with chevrons, long thin legs with banding, and the presence of tangled cobwebs in corners.
Similar Species
Often confused with Brown Widows (Latrodectus geometricus), but lacks the hourglass marking. Also similar to Steatoda (False Widows), which are typically darker and glossier.
Life Cycle
Females produce several pear-shaped, papery brown egg sacs throughout the year. One sac can contain hundreds of eggs. Spiderlings disperse via ballooning. Lifespan is usually about one year.
Ecological Importance
Major predator of indoor insect pests. They help regulate populations of disease-carrying insects like flies and mosquitoes in residential environments.
Conservation Status
Not evaluated by IUCN, but extremely common and widespread with no known threats.
Interesting Facts
Despite their small size, they can overpower prey much larger than themselves, including crickets and even small lizards, by quickly wrapping them in silk from a distance.
Photography Tips
Focus on the abdomen pattern and leg banding. Since they often reside in dark corners, using a soft flash or a side-light can help reveal the intricate patterns against a plain wall.
Identified: 2026-06-21T18:41:51.367316