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Harmless

Giant house spider

Eratigena atrica
Also called Tegenaria duellica, Tegenaria gigantea (older names)

Big, fast and startling, but not a threat to people; it runs away rather than bites.

Giant house spider, photo 1
Photo: Marcin Jasiński, CC BY 4.0, via iNaturalist
SizeBody about 13–18 mm (1/2 to 3/4 inch), sometimes up to about 25 mm (1 inch); leg span up to about 100 mm (4 inches) in large adults
Where in the houseBasement, garage, bathroom, living room, outside near the house
WhenMid-summer through early fall, peaking in late August to September when males are on the move.

Check these features

  1. Large brown to grayish-brown spider with a somewhat hairy, dull (not shiny) body
  2. Very long legs relative to the body; runs extremely fast across floors
  3. Faint pale pattern down the abdomen, though markings vary a lot
  4. Builds a flat sheet web with a funnel retreat in dark corners, wood piles or gaps in brick and stone
  5. Often found on the floor or stuck in a sink or bathtub

Bites and stings

Bites are very unlikely; the spider runs away rather than defending itself, and its bite is not known to harm people. If bitten, wash the area and watch it. See a doctor if redness spreads, the area becomes hot or swollen, or a sore develops, since skin infections are often mistaken for spider bites.

What to do

  1. Trap it under a jar, slide a card underneath and release it outside, or vacuum it up.
  2. If bitten, wash with soap and water and apply a cool cloth.
  3. See a doctor if a bite area spreads, becomes very painful or you develop a fever.
  4. If you want an ID, keep the spider intact in a jar for an extension office or expert.

Look-alikes

Hobo spider (Eratigena agrestis)Very similar but usually smaller (body about 8–14 mm); in western Washington the giant house spider is far more common. Only an expert with a microscope can be sure.
Wolf spidersHunt without webs, have a stockier body and two very large forward-facing eyes.
Barn funnel weaver (Tegenaria domestica)Much smaller, with clearly banded legs.

Why it came inside

Adult males roam in late summer and early fall looking for females and wander into homes; the spiders also live in basements, garages and wall gaps, and get trapped in tubs and sinks while seeking water.

Keep it out

  • Fit door sweeps on garage and basement doors and add weatherstripping.
  • Repair window screens and caulk gaps around pipes, wires and frames.
  • Inspect firewood outdoors and bring in only what you will burn right away.
  • Place sticky traps in dark corners of garages and basements in late summer.

What helps

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Sticky traps

Flat glue traps set along walls and in corners show what is moving through and where. Place them where pets and children can't reach.

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Door sweep

Closes the gap under an exterior door. If you can see daylight under the door, bugs can get in.

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Weatherstripping

Seals the gaps around doors and windows that let in drafts and bugs alike.

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Caulk and sealant

Silicone or siliconized acrylic caulk closes cracks around windows, pipes and baseboards. Bigger gaps need foam backer rod or expanding foam first.

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Screen repair kit

Patches or replaces torn window and door screens, one of the most common ways insects get in.

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Vacuum with a hose

Lets you remove bugs, webs and egg sacs without touching them. Empty the bag or canister outside right away.

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Bug catcher

A long-handled catcher moves a spider or insect outside without you having to touch it.

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Sources

  1. Washington State University Extension
  2. Oregon Department of Agriculture
  3. Oregon Department of Agriculture
  4. University of California IPM

Checked October 18, 2026. Rating backed by 3 sources. How we rate danger.