The biggest spider you’re likely to encounter in Washington state is the giant house spider, with a leg span reaching up to 4 inches. That’s roughly the width of your palm. These fast-moving spiders are the most common source of “what was THAT” moments in Washington homes, especially in fall when males go wandering in search of mates.
Giant House Spider
The giant house spider is Washington’s largest commonly encountered spider. Its body measures roughly half an inch to a full inch long, but it’s the legs that get people’s attention, stretching out to a total span of about 4 inches in large adults. They’re brown with mottled, slightly striped markings on the body and legs, which helps them blend into the dark corners they prefer.
These spiders are genuinely fast runners. They rely on speed rather than elaborate webs to catch prey, building funnel-shaped webs in corners, behind furniture, in garages, and in basements. If you’ve ever seen a large spider sprint across your living room floor, there’s a strong chance it was a giant house spider. Despite their alarming size and speed, they rarely bite, and bites that do occur are not medically significant for most people.
Giant house spiders are most common west of the Cascades, particularly in the Seattle, Tacoma, and Portland metro areas. They thrive in the mild, damp climate of the Pacific Northwest and have been established in the region for decades.
Hobo Spider
The hobo spider is another large funnel-web spider in Washington, though it’s smaller than the giant house spider, with a leg span typically around 1.5 to 2 inches. It’s brown and relatively plain-looking, lacking the distinct banding on the legs that many other spiders have. Telling it apart from the giant house spider can be tricky without a close look or a magnifying glass.
Hobo spiders have a complicated medical reputation. A CDC report from the 1990s documented cases of necrotic wounds from hobo spider bites in the Pacific Northwest, describing a pattern where an initially painless bite develops into blisters within 15 to 35 hours, followed by a cratered wound that can take 45 days or longer to heal. In bites over fatty tissue, healing sometimes took up to three years. Severe headaches were the most common systemic symptom, sometimes starting within 30 minutes and lasting a week.
That said, hobo spider venom has been debated for years. Many researchers now consider the evidence for necrotic bites weaker than initially reported, and the CDC no longer lists the hobo spider among spiders of medical concern. Many suspected spider bites turn out to be bacterial infections or other skin conditions. The practical takeaway: hobo spider bites are unlikely to be dangerous, but any wound that develops blistering or spreading redness deserves medical attention regardless of the cause.
Other Large Spiders in Washington
Cross orb weavers are the big spiders you’ll notice in gardens and around porch lights in late summer and fall. Females can have a body close to an inch long, and they build the classic circular webs that span doorways and fence gaps. Their round abdomens are marked with a distinctive white cross pattern. They look impressive but are harmless and excellent at catching mosquitoes and flies.
Wolf spiders are ground hunters found throughout Washington, both east and west of the Cascades. Larger species can reach a leg span of 2 to 3 inches. They don’t build webs at all. Instead they chase down prey on foot, and you’ll often spot them on the ground at night when their eyes reflect flashlight beams with a greenish glow. They occasionally wander indoors but strongly prefer being outside.
Black widows do live in eastern Washington, particularly in dry, undisturbed areas like woodpiles, sheds, and rock walls. They’re not especially large in leg span, but their shiny black body with a red hourglass marking makes them easy to identify. They’re the only spider in Washington with a medically significant bite that’s well-established in the scientific literature.
Why You See More Spiders in Fall
Autumn is mating season for most Northwest spider species, and that’s when sightings spike indoors. Female spiders generally stay put in their webs, but males roam widely looking for mates. According to WSU entomologists, about nine out of ten spiders people bring in for identification during fall are males on the move. They’re not invading your home for food. They’re wandering, and your house happens to be in the path.
Cold weather adds another layer. Spiders are looking for warm, sheltered spots to survive winter, and the gaps around your doors and windows are open invitations. This combination of mating behavior and temperature-seeking is why September through November is peak spider season in Washington.
Keeping Large Spiders Out of Your Home
The most effective approach is physical exclusion. Seal gaps around doors, windows, and foundation vents with weatherstripping or caulk. Pay special attention to garage doors, which often have gaps large enough for a 4-inch spider to walk right through. Install or repair door sweeps on exterior doors.
Inside, reduce the habitat they’re attracted to. Clear clutter in basements, garages, and storage areas. Spiders love undisturbed piles of boxes, shoes, and firewood. Sticky traps placed along baseboards and in corners are a simple way to monitor what’s coming in and catch wandering males before they end up in your bedroom.
Outdoor lighting attracts insects, and insects attract spiders. Switching porch lights to yellow or warm-toned LED bulbs reduces the insect buffet near your doors. Keeping vegetation, mulch, and woodpiles away from your home’s exterior also cuts down on the spider population right outside your walls.