Spiders in South Central Idaho

South central Idaho is home to a mixture of spiders that can be potentially dangerous and spiders that present no danger to humans. Even the two most dangerous spiders in Idaho, the hobo spider and black widow, rarely cause people harm. The easiest way to identify common spiders found in the state is to break them into groups, including spiders that create webs, spiders that hunt prey and spiders that are potentially dangerous.

  1. Western Black Widows

    • Adult female black widows are easy to identify in south central Idaho because they have a shiny, black and globular body. The body has a red hourglass shaped marking on the bottom. They have long skinny legs, and the overall size is 1 ½ inches in diameter when including the legs. The males are about half the size of females. Males are normally olive brown but can be black, and they have light stripes and a band down the middle. They are found throughout Idaho, but are most common in the southern third of the state. They are commonly found in bushes, woodpiles, under rocks, barns and dark corners of places like garages, sheds or basements.

    Hobo Spiders

    • The other spider of worry in south central Idaho is the Hobo spider. They can commonly be found in homes from mid-August to November. Hobo spiders arrived in Idaho in the 1960s and established themselves throughout the state by the 1990s. Hobo spiders stick to ground levels of homes because they are poor climbers. They build funnel shaped webs on ground levels and will wait in the back of the web for prey to get stuck in the web. Hobo spiders can be identified by their legs, which are uniformly colored either tan or brown, and their eyes which are uniformly sized and in two slightly curving groups of four.

    Web-Weaving Spiders

    • Common web-weaving spiders found in south central Idaho include funnel-web weaver spiders, orb weavers, and sheet-web spiders. These spiders capture their prey by creating silk webs. Funnel-web spiders create funnel shaped webs that are commonly found in tall grass, rocks, firewood piles and other good hiding places. Orb weaver spiders produce vertical "bulls-eye" looking spider webs that are used to capture flying insects. Sheet-web spiders are tiny spiders that produce giant horizontal webs on the ground that can capture insects. Many different species of these spiders can be found in Idaho, all with different distinctive characteristics, but can easily be identified as part of a larger group of spiders by their webs.

    Spiders that do not Spin Webs

    • There are also a large number of spider species in south central Idaho that do not build webs. These spider species include wolf spiders, crab spiders and jumping spiders. These spiders have good eyesight and will actually stalk or chase down prey when feeding. Jumping spiders can jump, and have two very large eyes on the front of their body. Crab spiders get their name because the way their carry their front legs makes them look like a crab. They are commonly found in flowers waiting for the prey to come to them. Wolf spiders are large spiders that have a big and hairy body. They may look scary, but are harmless to humans.