Common American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
Rounded, bulbous abdomen with a slightly flattened cephalothorax. The body texture is covered in fine hairs and the proportions show a typical theridiid build with a prominent, high-domed abdomen that often overhangs the cephalothorax.
Size Estimate
Body length ranges from 3 to 8 millimeters, with a leg span of roughly 1.5 to 2.5 centimeters. This appears to be a small adult or late-stage juvenile specimen.
Coloration & Markings
Mottled brown, tan, and cream coloration with chevron patterns or dark spots along the dorsal surface of the abdomen. The legs feature faint dark banding.
Web Type
Irregular tangle web (cobweb) constructed in corners, crevices, near ceilings, or inside porcelain basins like sinks and bathtubs where they occasionally get trapped.
Eye Arrangement
Eight small eyes arranged in two rows of four, typical of the family Theridiidae, with lateral eyes touching or closely grouped.
Leg Characteristics
Slender, tapering legs of moderate length with faint darker bands and small spines, lacking specialized heavy spination.
Venom & Safety Information
Venom Information
Contains mild neurotoxic venom used primarily to subdue small invertebrate prey.
Medical Significance
Harmless to humans. Bites are rare, typically only occurring if trapped against the skin, and result in mild, localized irritation similar to a mosquito bite.
Safety Recommendations
No special precautions needed. To relocate, gently guide the spider into a cup using a piece of cardstock and release it outdoors.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution worldwide; commonly found in human dwellings, outbuildings, barns, and protected outdoor niches.
Behavior & Temperament
Timid and non-aggressive; hangs upside down in its web and retreats rapidly when disturbed.
Diet & Prey
Feeds on a wide variety of small household insects including flies, ants, mosquitoes, and small beetles using sticky silk threads.
Seasonal Activity
Active year-round indoors, with increased movement and mating activity during the warmer spring and summer months.
Description
A familiar resident of homes worldwide, the American house spider is an unobtrusive cobweb weaver that helps control household pest populations.
Key Features
Bulbous, highly domed abdomen with brownish chevron patterns, combined with an irregular tangle web and a habit of hanging upside down.
Similar Species
Steatoda species (False Black Widows) and Latrodectus species (True Widows); distinguished by less glossy skin and lack of bright warning hourglass marks.
Life Cycle
Females produce several brownish, pear-shaped papery egg sacs containing hundreds of eggs. Spiderlings hatch and disperse via ballooning or crawling.
Ecological Importance
Serves as an effective natural pest controller inside human dwellings, significantly reducing indoor insect populations.
Conservation Status
Not evaluated by the IUCN, highly secure and abundant globally.
Interesting Facts
Females can live for several years and may produce multiple egg sacs from a single mating event.
Photography Tips
Use macro lenses with good lighting from above or the side to highlight the abdominal patterns while maintaining a safe focal distance.
Identified: 2026-09-19T07:18:22.109476