Common House Spiders of the Pacific Northwest

The Pacific Northwest is a region in western North America that includes the U.S. states of Oregon, Washington and the Candadian territory of British Columbia. At times Montana, Idaho, Southeast Alaska and northern California are included in the region. This area is lush with forests, rivers, lakes and access to the Pacific Ocean. With its cool, moist climate, the area provides ideal living conditions for many spiders. It is useful to know some facts about common house spiders in this area so that if you see one at home you know how to respond, since they can deliver painful bites and reproduce in your home.

  1. Giant House Spider

    • This spider is a member of the genus tegenaria and is a close relative of the domestic house spider and the hobo spider, both of which also reside in the Pacific Northwest. This spider is easily identifiable for its large size. Females can reach 0.7 inches in length with a leg span of roughly 1.7 inches, however some specimens have measured a leg span of three or four inches. These spiders have hairy legs that are very thin with a small abdomen. They come in shades of brown, muddy red and yellow. They have an appearance similar to the domestic house spider and unfortunately only a microscopic investigation will usually tell them apart. The giant house spider makes a flat, messy web with a funnel at one end, which the spider hides in to attack its prey. Males wander around for mates in the late summer and early autumn. They like to build their webs in corners, in attics and other places that are rarely disturbed. They are quite venomous, but only to their pray. They are not known to bite humans.

    Hobo Spider

    • This spider is considered "medically significant" because of its effects on its victims, which includes tissue death that results from lesions and blisters after the bite has been made. Hobo spiders only inject venom in about half of their bites. This spider also weaves a funnel web, similar to the giant house spider. Hobo spiders are not easy to identify by sight because there are so many other species of spiders that are similar looking. The females are slightly larger than the males at just 0.3 inches in length. Males have outgrowths resembling short legs near their mouth. The spiders are long legged and fast and are shades of brown, with no banding on the legs. They like to live in crevices and cracks that can support their funnel webs.

    Common House Spider

    • The common house spider is small and smooth (1/4 inch long with an inch long leg spread), with a round, almost spherical abdomen and striped brown legs. Its abdomen is a swirled pattern of brown and white. It makes a dense tangle of webs and lives its entire life inside the web. Because of the relative size of its abdomen, it can't move easily on the ground. The female makes oval-shaped egg sacs that house up to 500 eggs. Young spiders quickly disperse along a single strand of web, although many of them will eat by nearby spiders. They live between loose walls, behind open doors and in attic windows. They are not aggressive spiders and will only bite in self-defense. The bite hurts no more than a bee sting, and if venom is injected there could be swelling of the area. Some humans are allergic and have more severe symptoms to the venom; however, medical attention is not necessary and those bitten are prescribed rest.