Spiders in Southern Idaho

Southern Idaho is home to plenty of indoor and outdoor spiders. These creatures have eight legs and are members of the arachnids class. All spiders have two main sections for their bodies --- the abdomen and cephalothorax. Some spiders build cobwebs, while others rely on other methods to catch their prey. While in southern Idaho, you may encounter either one of these types of spiders.

  1. Web-Spinning Spiders

    • Spiders that spin webs are usually found near residential or commercial areas. These spiders may range from as small as a dime to as large as a quarter. The funnel-web weaver creates a flat cobweb with a funnel-shaped section under logs, stones or other protected areas. These spiders may also dwell in corners of walls, barns and basements. Funnel web spiders span from .59 to .79 inches in length and may appear tan to dark brown. The sheet-web spider is nearly an inch long. These spiders create dome-shape cobwebs on soils or among the leaves of plants.

    Active Hunters

    • Some Southern Idaho spiders are hunters that chase and capture food. A jumping spider is an active spider often seen on walls or windowsills. For example, the gray wall jumper is a jumping spider with black and white stripes over its body. Other jumping spiders may have a grayish-black body with white dots. Another jumping spider is the salticid jumping spider, and it is frequently spotted inside homes. Jumping spiders have an average length of .78 inches.

    Ambush Spiders

    • Some spiders in southern Idaho, such as folding-door and trapdoor spiders, prefer to pounce on unexpected insects for food. These spiders range in color from tan to black. The folding-door spider has slender, spiny legs with a flat, wide cephalothorax. It gets its name because it digs a burrow in soil and makes a collapsible silk cover for the top. The crab spider resembles an actual crab when it sits. These spiders usually wait for their prey on flowers, plants or vegetation. Crab spiders are beneficial because they eat numerous pest insects.

    Poisonous Spiders

    • The venom of some spiders found in the southern region of Idaho is poisonous to humans. The black widow may grow up to 1.5 inches in diameter. These spiders appear olive brown to black in color and have light color bands. Females bear the telltale red hourglass shape on their undersides. Black widows build loose, irregular cobs in dark areas. These spiders may also dwell under stones or live inside animals holes. Hobo spiders typically stay close to the ground since they are not good climbers. This type of spider is marked with triangular-shaped loops and appears tan and black in color. It grows to about .66 inches in length. Scientists disagree about the dangers of a hobo spider bite, but it is believe to kill tissue near the wound.