Penn State Extension


Common House Spider

Achaearanea tepidariorum

Achaearanea tepidariorum is a cosmopolitan spider that is widely distributed throughout most of the world. It is extremely common in barns and houses, where it constructs webs in the corners of walls, floor joists, and windows. The common house spider may also be found outside under objects such as rocks and boards, as well as beneath bridges and similar structures. In homes, it is most often encountered in damp areas such as basements and crawl spaces. Because this spider frequently abandons its web to build a new one nearby, it can produce many webs in a short period of time. This behavior causes homeowners much grief.


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The common house spider female is 5 to 6 millimeters in length with a yellowish-brown carapace and a dirty white to brown abdomen with gray chevrons. The legs are yellow, with darker rings at the end of each segment. Some individuals have a triangular, black spot on the top of the abdomen. The male is 3.8 to 4.7 millimeters in length with orange legs.

Life History

Males and females can be found at anytime of year, and there are reports of the spiders living for a year or more after maturing. The male and female will coexist in the web and mate repeatedly. The egg sacs are brown and ovoid with tough, papery covers and can be 6 to 9 millimeters in diameter. A female may deposit 12 or more egg sacs over her lifetime, each containing 140 to 380 eggs.

Medical Importance

Parasteatoda tepidariorum is not regarded as a medically important species. In fact, given this spider’s tendency to populate houses, plus the paucity of reported bites in the literature, it is apparent that the house spider does not often bite people. The few recorded and verified bites were accompanied by pain (increasing for 1 hour), red mark, or redness, with the duration of pain being 4 to 24 hours.

Authored by: Steve Jacobs, Sr. Extension Associate
March 2002 Revised 2015


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