Poisonous Spiders in Western Washington - Black Widows, Hobos, Yellow Sacs

Poisonous Spiders Found in Western Washington

The Pacific Northwest is home to a diverse population of spider species, most of which are harmless to humans. However, western Washington does have a few spiders whose bites can be medically significant for people. These spiders are not necessarily aggressive, but they will bite in self-defense if disturbed or unintentionally contacted.

Black Widow Spiders

The black widow spider (Latrodectus genus) is probably the most infamous poisonous spider in the United States. Female black widows are distinguished by the distinctive red hourglass shape on their undersides. They build messy cobwebs in sheltered spots like woodpiles, garages, sheds, and rarely used outdoor furniture.

The neurotoxic venom of a black widow bite affects the nervous system, causing symptoms like pain and rigidity in muscles, headache, nausea, vomiting, abdominal pain, tremors, and sweating. Their bites can be dangerous to young children, the elderly, or those with certain medical conditions, though deaths are rare with proper medical treatment.

Several black widow species are found west of the Cascades in Washington, including the western black widow (Latrodectus hesperus) and the northern black widow (Latrodectus variolus). They are generally not aggressive toward humans unless their webs are disturbed.

Brown Recluse Spiders

Despite widespread fears, true brown recluse spiders (Loxosceles reclusa) do not occur naturally in Washington state or anywhere on the West Coast. Sometimes their cousins, such as the desert recluse or Arizona recluse, are misidentified as brown recluses in the western U.S.

Brown recluse spiders are native to the South and Midwest. Their venom can cause painful skin lesions in some people who are bitten. But outside of their natural range, brown recluse sightings are usually case of mistaken identity. Various harmless spiders are often blamed as dangerous recluses.

Hobo Spiders

The hobo spider (Eratigena agrestis) is a member of the funnel weaver family (Agelenidae) found throughout the Pacific Northwest. They are large, fast-moving spiders that build funnel-shaped webs in dark places like basements and sheds. Hobo spiders sometimes wander indoors and become established in houses.

Hobo spider bites were once thought to cause severe skin injuries, but this has been controversial. Though their venom can produce minor effects like redness, pain, and itching in humans, medically significant wounds seem rare. Only a small percentage of bites lead to necrosis (cell death), which may also be due to bacterial infection.

Yellow Sac Spiders

Yellow sac spiders (Cheiracanthium genus) are one of the most common house spiders encountered by Washington residents. As their name suggests, they have pale yellow bodies and construct silken tubes or sacs where they hide during the day.

The bite of a yellow sac spider feels like a mild bee sting. Most of the time, their venom only causes temporary pain, redness, and itching. Rarely, bites may lead to localized skin necrosis. But there are no confirmed cases of severely toxic bites to humans in Washington.

Woodlouse Hunter Spiders

Woodlouse hunter spiders (Dysdera genus) are medium-sized spiders with a dark, shiny appearance and prominent fangs. As their name suggests, they prey primarily on woodlice. They are found under logs, rocks, and other debris west of the Cascades.

Though woodlouse hunters appear formidable, their venom is not very toxic. Bites generally produce mild reactions like local pain, redness, and swelling for a few hours. Serious symptoms are rare, even when these spiders bite defensively if mishandled. Their large fangs can produce a painful puncture wound.

Avoiding Spider Bites

While the vast majority of spiders in western Washington are harmless, here are some tips to protect yourself from bites:

• Carefully inspect or shake out clothing, shoes, towels, and bedding that have been left on the floor or outside.
• Wear gloves, long sleeves and pants when cleaning garages, sheds, woodpiles, and other seldom-used areas where spiders may live.
• Clear clutter and vacuum webs regularly to discourage spiders from taking up residence in your home.
• Be cautious when reaching into dark, infrequently accessed spots where spiders may dwell.
• If you have severe reactions to insect bites, keep emergency medications like epinephrine auto-injectors on hand.
• Teach children not to touch spiders and to alert adults if they find one.

As with any bite or sting, seek medical care right away if you experience serious symptoms like difficulty breathing, nausea, sweating, muscle cramping, or spreading skin lesions.

Spider Bite Identification and Treatment

If you receive what you suspect is a spider bite, try to capture and identify the spider if this can be done safely and without delaying treatment. Knowing the species can help medical professionals administer the proper care and anti-venom if needed.

Clean the bite area thoroughly with soap and water. Apply a cool compress to relieve swelling. Avoid scratching or irritating the wound, as this can lead to infection. Monitor for signs of allergic reaction, including rash, itching, swelling, and breathing difficulties.

Over-the-counter antihistamines and pain relievers may be used for mild symptoms. Seek emergency medical care if you experience worrying or severe reactions. Though rare, some spider bites can be life threatening without prompt treatment.

With caution and proper education, western Washington residents can coexist relatively safely with local spiders. A bite should not be cause for panic, but do take appropriate actions at the first signs of a dangerous reaction.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.