Common House Spider (Parasteatoda tepidariorum)

Common House Spider (Parasteatoda tepidariorum)

The Common House Spider (Parasteatoda tepidariorum), also known as the American House Spider, weaves an irregular web, called a cobweb, of a design often used as decoration at Halloween. It belongs to the family of Comb-footed Spiders (Theridiidae) and order, Araneae. Other members of this family are the poisonous Southern Black Widow Spider (Latrodectus mactans), Northern Black Widow Spider (Latrodectus variolus) and Western Black Widow Spider (Latrodectus hesperus). The bite of any of these female Black Widow Spiders usually requires medical treatment but the Southern Black Widow Spider is the most dangerous. However, the bite of even the Southern Black Widow Spider is not usually fatal. (The author was bitten by a Southern Black Widow Spider but did not seek medical treatment until an ulcer appeared. It is best to seek treatment as soon as possible after a bite.)  The male Black Widow Spiders do not bite.The Common House Spider's venom is not poisonous to people. These spiders look much alike but the Black Widow Spiders are blacker and the females have red markings. The three Black Widow Spiders are not native to Maine but may occur as "accidental tourists" in a shipment or a tourist's camping or hiking gear. Exercise caution around these creatures until identification is definitive.

Parasteatoda tepidariorum's body is about ¼ inch (6 millimeters) long but the entire spider can be as large as one inch (2.54 centimeters) when the legs are outstretched. The abdomen has black and gray streaks and spots. The male's legs are orange-brown with black bands. The female's legs are yellow with black bands. Generally, this spider appears brown to orange overall. It eats insects and helps control insect pests in the home. The Common House Spider has very poor eyesight. Therefore, one can get very close to it before it is alarmed. When threatened by humans, this spider will attempt to hide rather than bite. However, it will bite if grabbed and squeezed. Its venom is similar to that of the Black Widow Spider but much less toxic. People allergic to the venom may have a mild reaction to a bite that usually will not require medical attention.

 

Common House Spider (Parasteatoda tepidariorum)

Male and female Common House Spiders will share the same web. The female will build a brown, pear-shaped, silky egg sack in the web that contains from 100 to 400 eggs. Female Common House Spiders can live for more than one year. It is most active in darkness and will build webs in dark areas.

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