Species of Spiders in Washington State

There are more than 40,000 categorized arachnid species in the world and only 3,000 are native to North America. There is no such thing as a "non-poisonous" spider. All spiders are carnivorous predators and they all inject venom into their prey or bite victims. In Washington state, the Latrodectus hesperus is the only spider species dangerously venomous to humans. Although all spiders are capable of spinning silk, some species do not use webs to catch their prey. There are four commonly found species in Washington.

  1. Rhabidosa Rabida

    • Rhabidoas rabida (also known as the wolf spiders) have large, hairy, 1-inch long bodies with legs that span up to 2 inches in length. Their body color may range from blackish gray to brown. Two of its six eyes are noticeably larger than the others. The Rhabidosa rabida is a wandering spider living most of its life alone. Females carry the young on its back until the young spiders mature, which take approximately six months. These spiders are aggressive towards humans and although their bites hurt, they are not dangerous to humans.

    Latrodectus Hesperus

    • Latrodextus hesperus (also known as the western black widow spiders) have a body approximately 1.5 inches in diameter. The female is jet black with two red marks that join and resemble an hourglass. Males are striped with white or yellow markings on their abdomen. The Latrodestus hesperus is rarely found on the eastern side of Washington and finds the climate of the western side more ideal. This spider is often found living among piles of firewood and within crawlspaces around the house. If bitten, the affected area will become red and swollen and will be followed by intense muscular pain and difficulty breathing. Side effects will go away in three days if left untreated but treatment is advised.

    Tegenaria Agrestis

    • The Tegenaria agrestis (also known as the hobo or aggressive house spiders) are one of the most common spiders found in homes in Washington. The spider's body has a diameter of about 1 3/4 inches in diameter. It's a nocturnal spider spending its nights crawling on the floor for its prey. Tegenaria agrestis are rarely found climbing vertically. This species will bite with very little provocation. Its venom can cause a severe reaction in people who are allergic to spider venom.

    Miturgidae Cheiraicanthium

    • Miturgidae cheiracanthium (also known as the sac spiders) have a solid yellow or brown body with a diameter of about 3/8 inches. They are nocturnal hunters building small white sacs where they retreat during the day. At night they climb down walls hunting for prey. Miturgidae cheiracanthium do not spin webs to catch their prey and only spin silk when laying eggs, breeding or hibernating. Its bite is painful to humans but not dangerous.