Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
The spider features a bulbous, globular abdomen that is noticeably larger than the cephalothorax, typical of comb-footed spiders. The body texture is somewhat smooth with sparse, fine hairs. It is typically found hanging upside down in its irregular web tangle.
Size Estimate
Body length ranges from 5 to 8 millimeters for females, with a leg span of around 15 to 25 millimeters.
Coloration & Markings
Base coloration ranges from yellowish-brown to dark brown or grayish. The abdomen features mottled patterns, often with dark chevron-shaped or triangular markings, and sometimes lighter spots along the sides.
Web Type
Builds an irregular, three-dimensional cobweb (tangle web) in corners, window frames, and under eaves, constructed with sticky silk threads designed to catch walking or flying insects.
Eye Arrangement
Features eight eyes arranged in two rows of four, typical of the family Theridiidae, with small lateral eyes closely grouped together and larger median eyes.
Leg Characteristics
Legs are moderately long and thin, featuring faint darker banding along the segments. The hind tarsi possess a comb of serrated setae used to pull silk from the spinnerets.
Venom & Safety Information
Venom Information
Possesses mild neurotoxic venom used to immobilize small insect prey. It is not considered dangerous to humans.
Medical Significance
Negligible medical significance. Bites are rare, typically only occurring if the spider is trapped directly against human skin, resulting in minor localized pain and redness that resolves quickly.
Safety Recommendations
No specific safety precautions needed as they are harmless. If relocation is desired, gently guide the spider into a container using a piece of paper and release it outdoors.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution worldwide. Highly synanthropic, commonly found inside human dwellings, basements, sheds, garages, and around porches and window frames.
Behavior & Temperament
Timid and non-aggressive. When disturbed, it typically drops out of its web on a safety dragline or retreats into a dark crevice. It remains in its web continuously.
Diet & Prey
Feeds primarily on household pests including flies, mosquitoes, gnats, ants, and other small spiders caught in its web.
Seasonal Activity
Active year-round indoors in heated buildings, with increased activity, wandering, and mating observed during the warmer spring and summer months.
Description
The Common House Spider is a familiar and harmless indoor neighbor. Hanging unobtrusively in its messy web near windows or ceiling corners, this master of pest control quietly keeps populations of flies and mosquitoes in check.
Key Features
Globular, bulbous abdomen with mottled brownish markings, combined with an irregular three-dimensional cobweb structure in domestic human environments.
Similar Species
Steatoda species (False Widows), which tend to have a glossier, more darkly colored, and less patterned abdomen; and Latrodectus species (Black Widows), which lack the extensive mottled patterns and possess a distinct hourglass.
Life Cycle
Females produce several brownish, pear-shaped silk egg sacs containing hundreds of eggs. Spiderlings disperse via ballooning after hatching and mature over several months through multiple molts.
Ecological Importance
Acts as an effective natural biological control agent against household insect pests, helping to reduce insect populations indoors and around structures.
Conservation Status
Not evaluated by the IUCN; extremely common, widespread, and secure globally due to its close association with human habitats.
Interesting Facts
Despite living in close proximity to humans, they rarely bite and will often play dead or drop from their webs when gently disturbed rather than showing aggression.
Photography Tips
Use macro settings and good ambient lighting. Photograph from the side or slightly above to capture the pattern on the bulbous abdomen and the structure of the surrounding cobweb.
Identified: 2026-08-24T00:28:39.292660