Are Black Spiders in Washington State Dangerous? What You Need to Know

Most black spiders encountered in Washington State and Bellingham homes are completely harmless. The giant house spider — one of the most commonly seen large black-to-dark-brown spiders in the Pacific Northwest — is not medically significant. The western black widow is a Washington species, however, and a small black spider with a globular abdomen in a dry, sheltered spot deserves careful attention. The state Department of Health describes that spider as common to eastern Washington, and its range follows the drier country east and south of the Cascades, so it is uncommon on this side of them. Identification is the critical first step.

If you have found a large black spider in your Bellingham home and wondered whether it is dangerous, that is a reasonable question. Washington has dozens of spider species and several are black or very dark brown, so getting the identification right matters. The answer ranges from “completely harmless, actually beneficial” to “potentially medically significant, do not handle it.” This guide walks through the dark spiders most common in Whatcom County homes, how to tell them apart, and what to do if you have been bitten by one you cannot identify.

The black spiders you’ll actually encounter in Bellingham homes

Giant house spider (Eratigena duellica) — the most common black spider here

When homeowners call about a “huge black spider,” they are almost always describing the giant house spider. It is one of the most common spiders in the Pacific Northwest and responsible for the majority of alarming encounters in Whatcom County homes. Older references list it under the name Eratigena atrica, which is now treated as a doubtful catch-all name rather than the correct one for our local species.

• Size: Females can reach a leg span of 3–4 inches — genuinely large
• Color: Dark brown to black with a mottled abdomen; legs are dark and banded
• Web: Flat funnel-shaped web with a retreat at the narrow end, in corners, basements, and garages
• Behavior: Extremely fast in short bursts; retreats when disturbed; males wander in late summer and fall
• Medical significance: None to minimal — not considered medically significant

It is related to the hobo spider and cannot be separated from it by eye. WSU Extension states that without examining the very small reproductive structures you cannot definitively identify a hobo spider, which makes reliable separation a microscope job. Two things are worth knowing anyway. Banded legs work in one direction only: visible dark rings rule the hobo spider out, because hobo legs are uniformly colored — but plain legs prove nothing in return, since plenty of harmless funnel weavers have them. And the underside settles more than the top does: three or four pairs of pale spots on the sternum means it is not a hobo, while a pale central stripe there means it might be. For practical purposes both species are treated the same way: non-dangerous, though alarming.

Western black widow (Latrodectus hesperus) — Washington’s medically significant black spider

The western black widow is the spider that gives “black spider in Washington” its legitimate concern. The Washington State Department of Health describes it as common to eastern Washington, and that is the honest shape of its distribution: the range follows the drier, warmer country east and south of the Cascades, and Bellingham’s wet, cool climate is close to the opposite of what it wants. It is uncommon on this side of the mountains rather than routine. Where one does appear here, it is in a dry, sheltered, undisturbed location.

How to identify one:

• Body: Shiny, jet black — unlike the matte look of giant house spiders
• Abdomen: Distinctly globular and ball-shaped
• Red hourglass: A red to orange-red hourglass on the underside of the abdomen — not visible from above
• Size: About 1/2 inch body length — much smaller than a giant house spider
• Web: Irregular, messy, sticky cobweb — not a funnel web
• Habitat: Wood piles, under outdoor furniture, utility boxes, rarely disturbed garage corners

The key distinction: if the spider is very large (leg span over 2 inches), it is almost certainly NOT a black widow, whose body is only about 1/2 inch. If it is small, shiny black, and globular in a dry sheltered location, treat it as a potential black widow. Do not handle it — call for identification.

Hobo spider (Eratigena agrestis)

Brown and drab — not truly black, but often called black because of how it looks in dim light. Builds funnel webs at or near ground level. You will read that the chevron markings on the abdomen identify one; they do not, and it is worth being clear about why. Neither WSU Extension’s identification factsheet nor UC IPM’s pest note on the species uses the chevrons at all. Both go straight to the reproductive structures, which means a mature specimen and a microscope.

Hobo spiders spent years being blamed for necrotic skin wounds, and that claim has not held up. The studies behind it were later called into question, the CDC removed the hobo spider from its list of venomous spiders, and the Washington State Department of Health states that hobo spiders are not considered dangerous as previously thought and that no evidence links their venom to skin necrosis. They are also less common here than their name recognition suggests: WSU reports that west of the Cascades the giant house spider outnumbers them about three to one.

False black widow (Steatoda grossa)

Small, dark purple to black with a rounded abdomen and no hourglass, frequently mistaken for a true black widow. Non-dangerous, though a bite can cause mild localized symptoms (uncommon). It builds messy irregular webs in garages and basements, adding to the confusion. The tells: no hourglass marking, and a purple-brown rather than jet black color.

Black ground beetles and harvestmen — not spiders

Many “black spiders” reported by homeowners turn out to be harvestmen (daddy long legs, a different order altogether), black ground beetles, or other dark arthropods. Harvestmen have oval bodies, extremely long thin legs, and no waist — spiders have a distinct waist. They are completely harmless.

Where do black spiders live in Bellingham homes?

Giant house spider habitat

They prefer dark, undisturbed spaces for their funnel webs: basement corners, garages, under stairs, in closets, and behind rarely moved furniture. They are most visible in September and October when males roam for females, crossing open floors and ending up in bathtubs and sinks they cannot climb out of.

Black widow habitat in Whatcom County

Western black widows here are most likely in dry wood piles near structures, under patio and deck furniture, in meter and utility boxes, in rarely disturbed garage and shed corners, in dense shrubbery against warm south-facing walls, and in drier crawl spaces. They are almost never in the main living areas — they seek undisturbed, dry conditions that active household spaces do not provide. The garage and outdoor structures are the primary concern.

What should I do if I find a black spider I can’t identify?

• Do not handle it — trap it under a glass or container without touching it
• Observe from a safe distance: shiny or matte? Globular or flat and elongated? Smaller than a quarter or larger?
• If small (body under 1/2 inch), shiny black, and globular with a web in a dry sheltered location, treat it as a potential black widow and call for identification
• If large (leg span over 2 inches), matte brown to black with a funnel web, it is almost certainly a harmless giant house spider
• You can bring the spider to us in a sealed container and we will identify it at no charge
• If you can safely photograph it, clear shots of the top and underside of the abdomen help a lot

What if I’ve been bitten by a black spider in Washington?

If you have been bitten and are not certain of the identification:

• Note the time of the bite and photograph or preserve the spider if possible
• Clean the bite site with soap and water
• Apply ice wrapped in cloth to reduce swelling and pain
• Watch how it develops over the next few hours
• Seek immediate medical attention if you develop spreading redness, muscle cramping or spasms, nausea, sweating, difficulty breathing, or a rapid heart rate — these can indicate black widow envenomation
• Go to an emergency room if any of those whole-body symptoms develop; black widow venom acts on the nervous system and can progress

None of this is medical advice, and if you are worried about a bite the right move is to speak to a health professional or the Washington Poison Center rather than working from a web page.

Giant house spider bites, if they happen at all, cause mild local pain and redness that resolves within hours. Hobo spider bites are similar. Black widow bites warrant medical evaluation regardless of how they look at first.

Common questions about black spiders in Washington State

I found a huge black spider in my Bellingham bathroom. Is it a black widow?

Almost certainly not. The giant house spider — by far the most common large dark spider in Bellingham — regularly ends up in bathtubs and sinks because it falls in crossing the rim and cannot climb the smooth surface. They look alarming but are harmless. Black widows are small, about 1/2 inch, and almost never in active bathroom or kitchen areas. If yours was quarter-sized or larger, it is a giant house spider. If it is small, shiny black, and sphere-shaped, call for identification.

Are black widows common in Bellingham, WA?

No. The Washington State Department of Health describes the western black widow as common to eastern Washington, and the range follows the drier country east and south of the Cascades — the wetter, cooler coastal climate here is not the environment it wants. Uncommon does not mean absent, though, and the places to be careful are the dry undisturbed ones: wood piles, outdoor furniture, utility and meter boxes, and dry garage corners. Treat any small, shiny black spider with a globular abdomen in a spot like that with appropriate caution.

Are hobo spiders dangerous?

The old assessment has been substantially revised. For years hobo spiders were described as dangerously venomous and blamed for necrotic wounds, based on studies that have since been questioned and never replicated. The Washington State Department of Health now states that they are not considered dangerous as previously thought and that there is no evidence their venom has caused skin necrosis in people, and the CDC removed them from its venomous spider list — the current federal guidance for outdoor workers names only the black widow and the brown recluse. Bites, where they happen at all, cause mild local symptoms. If you are bitten by any spider and develop significant symptoms, seek medical evaluation.

I see black spiders in my garage every fall. Where are they coming from?

Fall is when giant house spider males leave their retreats to find females, making them highly visible and mobile. Your garage likely provides year-round harborage — stable temperature, abundant prey like silverfish and earwigs, and undisturbed corners for web building. The fall surge is those year-round residents becoming active. Professional treatment in late summer, plus reducing clutter and sealing the door-to-house gap, substantially lowers garage spider activity.

Do I need to call pest control for a black spider, or can I deal with it myself?

For individual spiders you can clearly identify as harmless — giant house spider, cellar spider, false black widow — DIY removal is entirely reasonable. Call a professional when you cannot clearly identify the spider and it could be a black widow, you are seeing large numbers regularly, DIY efforts keep failing, or you find a suspected black widow where children or pets have access. We will come out and take a look at no charge, tell you what you have, and say whether treatment is warranted, with no commitment either way.

What do black widow webs look like?

Western black widow webs are irregular, messy, three-dimensional cobwebs — not organized orb or funnel webs. They are built close to the ground or in sheltered corners and are notably strong and sticky, with a coarse, irregular look. The spider retreats to a small tubular shelter at the web’s edge. Finding a messy cobweb like this in a dry sheltered location — under outdoor furniture, in a low garage corner, in a utility box — is a reason to look carefully before reaching in.

My child found a small shiny black spider outside. Should I be concerned?

A small, shiny black spider with a globular abdomen in a dry, sheltered location warrants cautious attention. Tell your child not to touch it and call for identification. From a safe distance, look for the red hourglass on the underside, the jet black shine, and the round abdomen. If you cannot confirm it is harmless from observation alone, err on the side of caution. A suspected black widow bite in a child should be assessed by a doctor without delay.