Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae. Characterized by a comb-like row of bristles on the fourth leg tarsus and spherical 'tangle' webs.
Physical Description
A small spider with a bulbous, teardrop-shaped abdomen and a relatively small cephalothorax. The abdomen is often taller than it is long and slightly pointed at the rear. The body is covered in fine, short hairs.
Size Estimate
Females range from 5mm to 8mm in body length; leg span up to 25mm. Males are smaller (3.5mm-5mm). This looks to be an adult female.
Coloration & Markings
Mottled pattern of brown, tan, gray, and cream. The abdomen features irregular V-shaped chevrons and dark specks. The legs are typically pale with dark, distinct bandings at the joints.
Web Type
Tangle web or 'cobweb.' A messy, non-symmetrical structure of sticky silk often built in corners, under eaves, or between surfaces. It includes a denser retreat area where the spider hides.
Eye Arrangement
Eight eyes arranged in two rows of four. The anterior median eyes are dark; the others are pearly white. This arrangement is typical of theridiid spiders.
Leg Characteristics
Long, slender legs. The most diagnostic feature is the 'comb' of serrated bristles on the tarsus of the fourth pair of legs, used to throw silk over prey. Prominent dark banding is visible on this specimen.
Venom & Safety Information
Venom Information
The venom is a neurotoxin designed to paralyze insects but is not medically significant to humans. Potency is low, and the delivery system (fangs) is very small.
Medical Significance
Harmless. Bites are rare and usually occur only if the spider is squeezed. Symptoms are similar to a mild bee sting: localized redness, slight swelling, and itching that resolves quickly.
Safety Recommendations
No special safety measures required. If they are in an unwanted spot indoors, they can be easily moved outside using a cup and a piece of paper. Relocate to a garden or shed.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found worldwide. Highly associated with human structures (barns, sheds, houses). Prefers dark, humid environments but adapts well to gardens and fences.
Behavior & Temperament
Passive and non-aggressive. They are 'sit-and-wait' hunters that remain in their webs. When threatened, they often drop to the ground on a dragline or curl up into a ball to play dead.
Diet & Prey
Generalist predator eating flies, mosquitoes, ants, and other spiders. They can take down prey much larger than themselves by using their comb-feet to wrap the victim in silk from a distance.
Seasonal Activity
Active year-round in temperature-controlled indoor environments. Outdoors, they peak in late summer and autumn for mating; they may overwinter as juveniles or adults in sheltered spots.
Description
The quintessential 'cobweb' spider found in homes worldwide. These spiders are masters of domestic pest control, quietly occupying corners and managing insect populations without posing a threat to residents.
Key Features
Taller-than-long bulbous abdomen, mottled brown/tan coloration, banded legs, and the production of papery, teardrop-shaped egg sacs in a messy tangle web.
Similar Species
Steatoda species (False Widows) which have glossier bodies and less mottling; Parasteatoda simulans which is nearly identical but significantly smaller.
Life Cycle
Females produce distinctive brown, papery, pear-shaped egg sacs containing up to 400 eggs. They may produce several sacs in a season. Lifespan is approximately one year for females; less for males.
Ecological Importance
Critical for natural pest control in suburban and urban environments. They consume large quantities of nuisance insects like fungus gnats, mosquitoes, and flies.
Conservation Status
Not evaluated by the IUCN. They are extremely common and widespread with stable populations due to their ability to live alongside humans.
Interesting Facts
Despite their small size, they have been known to capture small lizards or even tiny snakes that get caught in their low-hanging webs. They also exhibit 'bridging' where they release silk to let air currents carry it to a new surface.
Photography Tips
Focus on the banding on the legs and the pattern on the side of the abdomen. Using a macro lens or 'portrait' mode can help blur the background silk to make the spider's shape pop.
Identified: 2026-07-06T22:25:38.064914