Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae. Characterized by building tangled, messy webs and having a comb-like row of bristles on their hind legs.
Physical Description
Small spider with a highly convex, bulbous abdomen that is larger than the cephalothorax. The body is teardrop or pear-shaped. They have a glossy texture but can appear dusty or mottled due to their markings.
Size Estimate
Females range from 5–8 mm in body length; males are smaller at 3–5 mm. Including legs, they typically span 15–20 mm.
Coloration & Markings
Variable tan, brown, and gray mottled patterns. The abdomen often features dark patches, chevrons, and light spots. Light-colored specimens may have a distinct 'U' or 'V' shaped mark on the dorsal side.
Web Type
Tangle web or 'cobweb'. These are irregular, non-symmetrical, and haphazardly constructed. They are often built in corners or between structural elements like the metal railing shown.
Eye Arrangement
Eight eyes in two rows of four. The anterior median eyes are often dark, while the others are pearly/light. This arrangement provides moderate movement detection.
Leg Characteristics
Long, slender legs. Tarsi of the fourth pair of legs have a 'comb' of serrated bristles used for flinging silk over prey. Legs are often banded with dark and light brown rings.
Venom & Safety Information
Venom Information
Contains latrodectrols, but far less potent than their relatives, the widows. The venom is designed to paralyze small insects and is not considered a threat to humans.
Medical Significance
Low medical significance. Bites are extremely rare and usually only occur if the spider is squeezed. Symptoms are typically limited to mild localized pain, swelling, or redness.
Safety Recommendations
Generally harmless. If you wish to remove them, use a duster or vacuum for webs, or gently relocate the spider using a cup and card. Wear gloves when cleaning old storage areas.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution, found worldwide. Predominantly synanthropic, living in close proximity to humans in houses, garages, sheds, and under railings or eaves.
Behavior & Temperament
Very timid and non-aggressive. They spend most of their time hanging upside down in the center of the web. If disturbed, they will drop to the ground or retreat to a corner.
Diet & Prey
Opportunistic hunters of flies, mosquitoes, ants, and other spiders. They use their silk to quickly entangle prey that wanders into the sticky 'trip wires' of the cobweb.
Seasonal Activity
Active year-round in temperature-controlled indoor environments; outdoors, they are most visible from late spring through autumn.
Description
An ubiquitous resident of human structures, the Common House Spider is the quintessential 'cobweb' maker. They are master architects of irregular silk scaffolding, providing free pest control for homeowners.
Key Features
Bulbous abdomen, mottled brown/gray pattern, tangled cobweb, and the distinctive papery teardrop-shaped egg sacs often found hanging in the web.
Similar Species
Steatoda borealis (False Widow) which is darker/glossier, and Latrodectus (Widow) species, which are typically black with red markings and lack the mottled brown pattern.
Life Cycle
Females produce brown, pear-shaped or spherical papery egg sacs. A single female can produce several sacs in a season. Lifespan is generally around one year.
Ecological Importance
Significant natural pest control agents in and around urban dwellings, reducing populations of flies and nuisance insects.
Conservation Status
Not evaluated by IUCN; they are abundant and widespread with no known threats.
Interesting Facts
They are capable of killing prey much larger than themselves, including small lizards or large cockroaches, by using their comb-feet to lash them with silk from a distance.
Photography Tips
Focus on the abdomen pattern and the shape of the egg sac if present. Use a macro lens or high zoom to capture the banded legs against the messy web background.
Identified: 2026-06-22T22:55:32.418436