7 Biting Spiders in Washington State That Actually Require Medical Attention

While walking through your basement last week, you likely brushed past several spider webs without a second thought.

Here’s what might surprise you: nearly all spiders are venomous to some extent, yet very few are harmful to people according to the Washington State Department of Health.

Understanding which biting spiders in Washington state actually warrant concern can save you from unnecessary panic while ensuring you recognize genuine medical emergencies.

You’ll discover how to identify the truly dangerous species, distinguish serious bites from harmless ones, and know exactly when to seek immediate medical care.

Most importantly, you’ll learn why the vast majority of spider encounters in Washington pose no real threat to your health.

Western Black Widow (Latrodectus hesperus)

The western black widow represents the most medically significant biting spider in Washington state. These spiders primarily inhabit eastern Washington but small populations exist in western regions near urban areas.

Female black widows measure about half an inch in body length with glossy black coloration. The distinctive red hourglass marking on their abdomen’s underside serves as the most reliable identification feature, though this marking can sometimes appear as two separate dots or a single mark.

Male black widows pose virtually no threat, measuring much smaller with brown coloration and white markings. They rarely bite and lack sufficient venom to cause medical issues.

Bite Characteristics and Symptoms:

• Initial bite feels like a pinprick or may go unnoticed
• Muscle cramping develops within 1-6 hours
• Severe abdominal pain mimicking appendicitis
• Rigid abdominal muscles without tenderness
• Profuse sweating and elevated blood pressure

Pro Tip: Black widow bites require immediate medical attention. Antivenom treatment proves most effective when administered within the first few hours.

Yellow Sac Spider (Cheiracanthium mildei)

Yellow sac spiders cause more medically significant bites in Washington than any other species. These pale yellow to light green spiders measure 5-10mm in body length and commonly enter homes seeking shelter.

You’ll often find them in corners where walls meet ceilings, inside silk sacs they construct for daytime retreats. Unlike web-building spiders, yellow sac spiders actively hunt at night, increasing human contact opportunities.

Identification Features:

• Pale yellow to light green coloration
• Darker stripe down the abdomen center
• Long, thin legs relative to body size
• No distinctive markings or patterns

The bite initially causes sharp pain followed by localized swelling and redness. Within 2-8 hours, a small blister may form at the bite site. Most bites heal completely within 1-2 weeks without complications, though secondary bacterial infections can occur if wounds aren’t kept clean.

Common Mistake: Many people mistake yellow sac spider bites for brown recluse bites, but brown recluse spiders don’t naturally occur in Washington state.

Hobo Spider (Eratigena agrestis)

The hobo spider controversy continues among medical professionals, with recent research suggesting they pose less danger than previously believed. These large, brown spiders measure up to 2/3 inch in body length and create funnel-shaped webs in dark, moist areas.

Key Identification Points:

• Brown coloration with darker leg bands
• Chevron pattern on abdomen (often faint)
• Funnel-shaped web with trip lines
• Poor eyesight leads to aggressive defensive behavior

Historical reports attributed severe necrotic wounds to hobo spider bites, but current scientific evidence questions this connection. Many alleged hobo spider bite cases likely resulted from other causes including bacterial infections or different spider species.

Key Takeaway: While hobo spiders can bite defensively, they rarely cause more than localized pain and mild swelling lasting 24-48 hours.

Giant House Spider (Eratigena duellica)

Giant house spiders frequently get mistaken for hobo spiders due to their similar appearance and size. These impressive spiders can reach over one inch in leg span, making them among Washington’s largest house-dwelling species.

You’ll typically encounter them in basements, crawl spaces, and garages where they build sheet webs with funnel retreats. Despite their intimidating size, giant house spiders rarely bite humans and their venom causes only minor local irritation.

Distinguishing Features:

• Larger than hobo spiders
• More robust leg structure
• Darker overall coloration
• Less aggressive when disturbed

Male giant house spiders become more visible during fall mating season as they abandon their webs to search for females. This seasonal activity often leads to increased human encounters but rarely results in bites.

Prevention Focus: Reducing moisture and sealing entry points proves more effective than chemical treatments for controlling giant house spider populations.

Wolf Spiders (Hogna spp.)

Wolf spiders in Washington include several species that hunt actively rather than building webs. These robust spiders measure 10-35mm in body length with excellent vision and rapid movement capabilities.

Mother wolf spiders carry egg sacs attached to their spinnerets, later carrying spiderlings on their backs for several weeks. This behavior, while fascinating, sometimes alarms homeowners who mistake the spiderlings for a single large, hairy spider.

Physical Characteristics:

• Robust, hairy appearance
• Excellent eyesight with large front eyes
• Brown and gray camouflage coloration
• Distinctive eye arrangement in three rows

Wolf spider bites typically cause only minor pain and swelling comparable to bee stings. The bite site may show two small puncture wounds but rarely develops into anything requiring medical attention.

Orb-weaver Spiders (Araneus spp.)

Orb-weaver spiders create the classic circular webs most people associate with spiders. Washington hosts numerous orb-weaver species ranging from tiny to quite large, with the cross orb-weaver being among the most common.

These spiders rarely bite humans, preferring to drop from their webs or play dead when threatened. Their fangs often can’t penetrate human skin, and even successful bites cause only minor local irritation.

Garden Benefits:

• Consume large quantities of flying insects
• Help control mosquito and fly populations
• Indicate healthy ecosystem balance
• Pose no significant threat to humans or pets

Orb-weavers typically rebuild their webs daily, consuming the old web for protein recycling. This behavior makes them highly efficient pest controllers in garden environments.

Pro Tip: Preserve orb-weaver webs in garden areas where they don’t interfere with human activity. They’ll significantly reduce flying insect populations naturally.

Jumping Spiders (Phidippus spp.)

Jumping spiders represent some of Washington’s most charismatic spider species. These small, compact spiders measure 4-18mm in body length and display remarkable intelligence and curiosity compared to other spider families.

Their exceptional vision allows them to track movement from several feet away, often appearing to “watch” humans with their large front eyes. This behavior, combined with their ability to leap many times their body length, can startle people despite their harmless nature.

Distinctive Traits:

• Compact, robust build
• Large, forward-facing eyes
• Metallic or iridescent coloration
• Curious, alert behavior

Jumping spiders rarely bite humans, and when they do, the bite resembles a minor pinprick with no lasting effects. They prefer hunting small insects and avoid human contact when possible.

Common Misconception: Despite their active hunting behavior and impressive jumping ability, these spiders pose no danger to humans and actually help control pest insects.

When to Seek Medical Attention:

Immediate medical care becomes necessary when you experience:

• Severe muscle cramping or rigid abdominal muscles (potential black widow bite)
• Difficulty breathing or swallowing
• Rapidly spreading redness or red streaking from the bite site
• Signs of systemic illness including fever, chills, or nausea
• Bite wounds that don’t heal or show signs of infection after 48 hours

Most spider bites in Washington require only basic first aid including cleaning the wound, applying ice, and monitoring for infection signs. However, don’t hesitate to contact healthcare providers when symptoms seem disproportionate to a simple spider bite.

First Aid Summary:

1. Clean the bite area with soap and water
2. Apply ice to reduce swelling and pain
3. Elevate the affected area if possible
4. Monitor for worsening symptoms
5. Seek medical attention for severe or unusual reactions

Understanding these biting spiders in Washington state helps you respond appropriately to encounters while avoiding unnecessary fear.

Remember that serious medical complications from spider bites remain extremely rare in the Pacific Northwest, but proper identification and response can ensure your safety during the occasional spider encounter.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. Always consult healthcare providers for proper diagnosis and treatment of suspected spider bites.