Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae. Key family characteristics include comb-like setae on the fourth tarsus used to pull silk over prey.
Physical Description
Rounded, bulbous abdomen that is notably high and somewhat pointed at the rear, joined to a smaller cephalothorax. The body is relatively smooth with fine hairs, and females exhibit a distinctly larger, swollen abdomen compared to males.
Size Estimate
Body length ranges from 5 to 8 millimeters for females (males are slightly smaller at 3.8 to 4.7 millimeters), with a leg span of roughly 15 to 25 millimeters. This appears to be an adult female specimen.
Coloration & Markings
Variable base coloration ranging from yellowish-brown to dark brown or grayish. The abdomen features a pattern of dark chevrons, spots, or lines, often bordered with lighter white or yellowish highlights.
Web Type
Tangle web or cobweb, consisting of a messy, three-dimensional array of sticky silk threads constructed in corners, crevices, and structural angles.
Eye Arrangement
Eight eyes arranged in two rows of four, with the lateral eyes touching or closely spaced, typical of the Theridiidae family.
Leg Characteristics
Long and slender legs with distinct dark banding or rings. They lack heavy spination but possess the characteristic comb-like structures on the hind tarsi for manipulating web silk.
Venom & Safety Information
Venom Information
Neurotoxic venom designed to quickly immobilize small invertebrate prey. It is not potent or dangerous to humans.
Medical Significance
Harmless to humans. Bites are rare, typically only occurring if the spider is squeezed or trapped against the skin, and result in minor, temporary local pain or mild swelling similar to a mosquito bite.
Safety Recommendations
No special safety measures are required. If relocation is desired, gently guide the spider into a container using a piece of cardstock and release it outdoors.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution worldwide. Highly synanthropic, commonly found in and around human habitations, basements, sheds, crawlspaces, and sheltered outdoor vegetation.
Behavior & Temperament
Timid and non-aggressive. They spend nearly all their time hanging upside down in the center of their webs, retreating rapidly when disturbed or dropping to the ground on a dragline.
Diet & Prey
Generalist predator feeding on crawling and flying insects such as flies, mosquitoes, beetles, ants, and other spiders caught in the web.
Seasonal Activity
Active year-round indoors, with peak mating and web-building activity occurring during the warmer spring and summer months outdoors.
Description
The Common House Spider is an inconspicuous yet beneficial neighbor found in homes across the globe. Recognizable by its bulbous, patterned abdomen and chaotic cobweb, this expert architect quietly patrols indoor and outdoor corners, helping keep pest insect populations in check without posing any threat to humans.
Key Features
Bulbous, teardrop-shaped abdomen with chevron markings, messy three-dimensional cobweb structure, and a preference for human dwellings and dark corners.
Similar Species
Steatoda species (False Black Widows) and Latrodectus species (True Black Widows). They can be distinguished by the lack of bright warning colors like red hourglasses and generally lighter, patterned abdomens.
Life Cycle
Females construct brownish, pear-shaped silk egg sacs containing up to several hundred eggs. Spiderlings disperse via ballooning after hatching. They undergo multiple molts over a lifespan of about one year.
Ecological Importance
Acts as an effective natural pest control agent in domestic and garden environments, helping regulate populations of nuisance and disease-vector insects.
Conservation Status
Not evaluated by the IUCN, but populations are extremely secure, abundant, and widespread globally due to their close association with human habitats.
Interesting Facts
Common house spiders can adjust the tension of their web threads to detect different types of vibrations, allowing them to distinguish between potential prey, mates, and dangerous predators.
Photography Tips
Use macro settings with a diffused light source or flash to highlight the abdominal patterns. Photograph from the side or slightly above while the spider is stationary in its web.
Identified: 2026-09-11T19:59:36.331500