Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
The spider features a bulbous, highly spherical to teardrop-shaped abdomen that is considerably larger than its small, oval cephalothorax. The surface has a slightly glossy to fine hairy texture. In this image, the spider is curled up defensively, displaying its ventral side and tucked legs.
Size Estimate
Body length approximately 5-8 mm for females (excluding legs), with a total leg span around 15-22 mm. The swollen abdomen suggests a mature adult female.
Coloration & Markings
Variable coloration ranging from tan and yellowish-brown to dark mottled brown. The abdomen exhibits off-white, grayish, and dark brown speckles, patches, and chevrons. The legs are light translucent brown with faint darker bands at the joints.
Web Type
Builds messy, three-dimensional tangle webs or cobwebs in secluded dark corners, sheds, basements, and window frames. The silk is non-sticky except for tension lines anchored near the ground.
Eye Arrangement
Eight small eyes arranged in two transverse rows of four on the anterior front of the cephalothorax, typical of Theridiidae spiders.
Leg Characteristics
Slender, delicate legs with thin joints. The first pair of legs is noticeably longer than the rest. The tarsus of the fourth leg features a row of serrated bristles forming a comb-like structure used to wrap prey in silk.
Venom & Safety Information
Venom Information
Contains mild neurotoxic venom designed to subdue small invertebrate prey. The venom is harmless to humans and lacks medical significance.
Medical Significance
Harmless to humans. Bites are extremely rare due to their timid nature and weak chelicerae, which struggle to pierce human skin. If a bite occurs, symptoms are limited to minor localized redness, swelling, or mild stinging akin to a mosquito bite.
Safety Recommendations
No danger to humans or pets. If found indoors and undesired, carefully scoop the spider up into a cup using a piece of paper or cardboard and relocate it to a garden, shed, or sheltered outdoor area.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution found globally worldwide. Highly synanthropic, predominantly inhabiting man-made structures such as houses, garages, basements, sheds, and outdoor porches.
Behavior & Temperament
Extremely docile, timid, and non-aggressive. When disturbed or removed from its web, it frequently feigns death by curling its legs tightly against its body (thanatosis), as shown in the image.
Diet & Prey
Feeds primarily on small flying and crawling insects such as flies, mosquitoes, ants, beetles, and wasps. They are capable of capturing prey larger than themselves using sticky trap threads.
Seasonal Activity
Active year-round indoors in climate-controlled structures. Outdoors, peak activity occurs from late spring through autumn, with mating occurring in early summer.
Description
The Common House Spider (Parasteatoda tepidariorum) is one of the most widespread arachnids found around human habitations. Recognizable by its rounded abdomen and mottled brown coloration, this unobtrusive creature plays a vital role as a natural pest manager in domestic environments.
Key Features
Spherical, mottled tan-and-brown abdomen; long slender legs with banded joints; habit of curling into a tight ball when threatened; presence in characteristic tangled cobwebs.
Similar Species
Steatoda grossa (False Black Widow) which is usually darker brown or purplish-black without heavy mottling; Latrodectus geometricus (Brown Widow) which possesses a distinct orange/red hourglass on the underside; and various Araneus orb-weavers.
Life Cycle
Females produce several brownish, pear-shaped or spherical egg sacs suspended within their webs. Spiderlings emerge and disperse via ballooning. Lifespan is typically 1 to 2 years.
Ecological Importance
Acts as an effective biological pest control agent inside homes and gardens, consuming significant numbers of nuisance insects such as flies, mosquitoes, gnat swarms, and cockroaches.
Conservation Status
Not evaluated by the IUCN; abundant and secure globally with stable populations due to human habitation expansion.
Interesting Facts
When threatened, these spiders drop out of their web and play dead (thanatosis) to fool predators. A single female can produce over a dozen egg sacs in her lifetime, housing thousands of spiderlings.
Photography Tips
Focus on the dorsal or ventral patterns and eye cluster. Because they curl into a tight ball when disturbed, allow the spider a few minutes of stillness in a web or gentle container so it uncurls its legs for a clear full-body shot.
Identified: 2026-07-22T18:36:16.420624