Common American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
The body features a bulbous, globular abdomen and a smaller cephalothorax. The abdomen is notably rounded and rises high above the spinnerets, giving it a somewhat teardrop or humpbacked profile when hanging upside down in its web. The overall texture is smooth with fine hairs.
Size Estimate
Body length ranges from 5 to 8 mm for females and slightly smaller for males, with a leg span up to 2.5 cm. This specimen appears to be an adult.
Coloration & Markings
Base coloration ranges from yellowish-brown to dark brown or grayish. The abdomen typically displays mottled dark brown or black chevron patterns, spots, or lines, often with lighter borders.
Web Type
Builds an irregular three-dimensional tangle web, commonly known as a cobweb, constructed in corners, under eaves, or near human dwellings where flying insects are abundant.
Eye Arrangement
Eight eyes arranged in two slightly curved rows of four, with the lateral eyes touching or closely spaced, typical of the Theridiidae family.
Leg Characteristics
Legs are moderately long, slender, and distinctly banded with alternating light and dark brown rings. They lack heavy spination and are held loosely within the tangle web.
Venom & Safety Information
Venom Information
Neurotoxic venom designed to immobilize small insect prey. It is of low potency to humans and not medically significant.
Medical Significance
Harmless to humans. Bites are extremely rare and typically only occur if the spider is squeezed directly against the skin, resulting in minor, localized redness or mild discomfort similar to a mosquito bite.
Safety Recommendations
No special precautions needed. If relocation is desired, gently guide the spider into a container using a piece of card and release it outdoors.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution, highly common in and around human habitations, basements, sheds, garages, and outdoor structures globally.
Behavior & Temperament
Timid and non-aggressive. When disturbed, it typically retreats to a secluded hiding spot nearby or drops from the web on a silken thread.
Diet & Prey
Feeds primarily on small flying and crawling insects such as flies, mosquitoes, ants, and beetles caught in its cobweb.
Seasonal Activity
Active year-round indoors, with peak outdoor activity and reproduction occurring during the warmer spring and summer months.
Description
The Common American House Spider is a familiar and harmless neighbor found worldwide. Hanging upside down in its messy cobweb in a dark corner, it patiently waits for unsuspecting insect pests, serving as a natural and effective form of pest control.
Key Features
Globular, humpbacked abdomen, mottled brown and cream chevron patterns, banded legs, and an irregular three-dimensional cobweb.
Similar Species
Steatoda species (False Black Widows), which generally have a glossier, more darkly colored, and less patterned abdomen.
Life Cycle
Females produce several brownish, pear-shaped silk egg sacs containing hundreds of eggs. Spiderlings disperse via ballooning after hatching, undergoing multiple molts to reach maturity within a year.
Ecological Importance
Acts as an effective biological control agent by consuming large numbers of household insect pests.
Conservation Status
Not evaluated by the IUCN, highly secure and abundant globally due to its close association with human habitats.
Interesting Facts
They are remarkably adaptable urban dwellers and can survive for extended periods without food if water is available.
Photography Tips
Use macro lenses with good side lighting to highlight the abdominal patterns and leg banding while maintaining a safe distance from the web.
User Notes
Outside
Identified: 2026-09-27T19:52:26.732078