Common American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
The spider has a bulbous, rounded abdomen that is considerably larger than the cephalothorax, typical of cobweb spiders. It features a moderately hairy body with long, tapering legs.
Size Estimate
Females typically range from 5 to 8 mm in body length, while males are slightly smaller at 3.8 to 4.7 mm, with an overall leg span roughly 2 to 3 times the body length.
Coloration & Markings
Variable coloration ranging from yellowish-brown to dark brown or nearly black, featuring chevron or triangular markings along the upper surface of the abdomen, sometimes interspersed with lighter or darker spots.
Web Type
Tangle web or cobweb, consisting of a three-dimensional, irregular scaffolding of sticky silk threads constructed in corners, under furniture, or beneath wooden structures.
Eye Arrangement
Eight small eyes arranged in two slightly curved horizontal rows across the anterior portion of the cephalothorax.
Leg Characteristics
Long, slender legs with distinct dark banding or rings, lacking heavy spination but equipped with combs on the tarsi for manipulating silk.
Venom & Safety Information
Venom Information
Neurotoxic venom primarily targeted at small invertebrate prey; generally weak and ineffective against larger animals or humans.
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; simply relocate them outside using a cup and paper if they are in an unwanted area, as they pose no threat.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution globally; commonly found indoors in human dwellings, garages, basements, and outdoors under rocks, tree bark, and wooden patio structures.
Behavior & Temperament
Timid and non-aggressive; hangs upside down in its web and retreats when disturbed or vibrates rapidly in the web as a defense mechanism.
Diet & Prey
Feeds on a wide variety of small crawling and flying insects, including ants, flies, mosquitoes, and other spiders, using sticky silk to entangle prey before subduing it.
Seasonal Activity
Active year-round indoors due to climate control, with peak breeding and visibility during the warmer spring and summer months outdoors.
Description
The Common American House Spider is a familiar and harmless inhabitant of human structures worldwide. Recognized by its bulbous abdomen and messy corner webs, it plays a beneficial role in controlling household insect populations.
Key Features
Bulbous, rounded abdomen; irregular three-dimensional cobweb; banded legs; brownish coloration with chevron markings.
Similar Species
Steatoda grossa (False Black Widow), which is darker, glossier, and has a more robust build; Latrodectus species (Black Widows), which have distinct red hourglass markings.
Life Cycle
Females produce several brownish, pear-shaped silk egg sacs containing up to several hundred eggs, which hatch into spiderlings that disperse via ballooning or crawling after a series of molts.
Ecological Importance
Serves as an effective natural pest controller in homes and gardens by reducing populations of common nuisance insects.
Conservation Status
Not evaluated by the IUCN, but populations are secure, abundant, and widespread globally.
Interesting Facts
Females can produce multiple egg sacs from a single mating and may live for several years in protected indoor environments.
Photography Tips
Use a macro lens with good side lighting to highlight the abdominal patterns and leg banding, maintaining a steady hand since they rest inside vibration-sensitive webs.
Identified: 2026-08-28T22:15:20.057187