Common Black & White Idaho Spiders

Spiders have long been the subject of human fascination and fear, though any misgivings about these tiny arachnids are usually unwarranted. Spiders are rarely dangerous and often help control populations of other pests. In Idaho, there are a number of spider species that are black or white in color, often separated by family.

  1. Cobweb Weavers

    • Cobweb weavers make up 234 different spider species within North America, many of which live in Idaho. With pea-shaped abdomens and thin, long legs, cobweb weaver spiders weave webs to catch prey. They can be black and white, brown, or entirely black. Cobweb weavers can live permanently in homes, as long as there is a consistent food source. They also live in old animal burrows, barns and in other protected, enclosed areas.

      One of the most infamous Theridiidae spiders is the black widow species, found throughout the state of Idaho and most common in the southern portion of the state. A black widow's bite can fatal, though this is rare, and those who have been bitten should seek medical help immediately. The mature female is the most harmful black widow spider, recognizable by her all-black color with a small red hour-glass shape on her abdomen.

    Jumping Spiders

    • Jumping spiders do not construct webs to capture prey like cobweb spiders. Instead, they hunt in a way that is similar to cats, stalking and eventually jumping onto and attacking prey. Among the 315 species, jumping spiders can range in color from reddish-brown to white or black. The most common jumping spider species in Idaho is the gray wall jumper, which is marked by alternating bands of black and white. Because they rely on eyesight to hunt, jumping spiders have some of the best eyesight of any spider family. They generally live outside, though they can wander accidentally into homes.

    Trapdoor Spiders

    • There are 39 different species of trapdoor spiders in North America. Tan or black in color, these spiders tend to lie motionlessly and wait for prey to approach before attacking.

      In Idaho, the most common kind of trapdoor spider is the folding-door spider. This name refers to the burrow that the spider builds to help capture prey. They can grow up to 1.5 inches in length with their legs extended. They do not generally live indoors and rarely attack people or pets. If provoked, they may still bite, though this is only about as harmful as a bee sting.

    Crab Spiders

    • Made up of 130 different North American species, crab spiders are part of the Thomisidae family of spiders. This family's nickname comes from the fact that this group of spiders' front legs look similar to the claws of a crab. Like trapdoor spiders, crab spiders also sit and wait for prey, though they do not build burrows to hide in. Rather, crab spiders usually sit and wait on flowers or on the soil. These spiders are often white or bright in color to blend in with the flowers they sit on. They can also be black, brown, or both black and white, and some can change colors to match the surrounding area.

    Wolf Spiders

    • There are 238 types of wolf spider species in the U.S., some of which reside in Idaho. They tend to be greyish-black with darker black flecks of color, and the largest species in the state can grow up to 2 inches in diameter including their leg span. Wolf spiders have six eyes, two of which are much larger than the rest, that look almost like headlights. Like nearly all spiders in Idaho, wolf spiders are not dangerous to people.