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Pest NameDescription 
Giant house spiderGiant house spiderThe giant house spider,<i>Eratigena atrica </i> (formally known as <i>Tegenaria gigantea </i> and <i>T. duellica</i>), is commonly found in and around Washington homes west of the Cascade Mountains. Its range also includes parts of coastal Canada and Oregon. They are not found east of the Cascades in Washington. It is often seen in mid-summer to early fall, when males in particular are highly mobile. These brown to grayish-brown spiders are highly variable in size and color. The body is typically around 1/2 inch to 1 inch in length (not including the legs); while the leg span for large adults can reach up to 4 inches. The smaller males are often mistaken for hobo spiders; however, in the Puget Sound region giant house spiders outnumber hobo spiders and are much more frequently encountered. The legs and body of the giant house spider are somewhat hairy and are not shiny in appearance. The color varies widely from light to dark, with markings on the body and legs ranging from barely visible to very distinct. Because of the variability in color, size, and markings, none of these are reliable features for identifying this spider. Giant house spiders prefer dark areas for web-building and are ideally adapted to life indoors. They are often found in garages or basements, as well as outdoors in firewood or in gaps between bricks or stones. They build sheets of webbing with a funnel-like hole in the center, where the spider sits waiting for prey. The giant house spider is not an extremely active climber and indoors is usually found on the floor or trapped in sinks or bathtubs where it has ventured in search of water. These spiders are not aggressive and usually run away (very quickly) when startled. The bite of the giant house spider is not known to pose any threat to humans. However, if you are bitten by a spider, bring the spider to an expert for correct identification and you may wish to seek medical attention. Spiders are considered beneficial because they are predators. However, they can also be a nuisance pest indoors. Giant house spiders are frequently mistaken for hobo spiders. For more information, see the following publication: Common Spiders of Washington EM113E at