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Harmless

Common house spider

Parasteatoda tepidariorum
Also called American house spider, house cobweb spider

Harmless: this is the small brownish cobweb spider found in corners and window frames, and it almost never bites.

Common house spider, photo 1
Photo: Erin Lalime, CC BY 4.0, via iNaturalist
SizeFemales 5–8 mm (about 1/5 to 1/3 inch); males about 4 mm (about 1/6 inch)
Where in the houseWindows and walls, basement, garage, attic, closets, outside near the house
WhenYear-round indoors; most noticeable in spring through fall.

Check these features

  1. Round, high, teardrop-shaped abdomen in mottled gray, tan and brown
  2. Faint chevrons and a small pale spot near the top of the abdomen
  3. Yellow-brown legs with darker bands
  4. Hangs upside down in a messy tangle web in a corner or window frame
  5. Brown, pear-shaped egg sacs hanging in the web

Bites and stings

Very rarely bites; it retreats when disturbed. The few known bites usually caused little or no reaction. As with any bite, get medical advice if you see spreading redness, signs of infection, or an allergic reaction.

What to do

  1. No danger to worry about: leave it, or remove it and its web.
  2. Vacuum the spider, web and egg sacs if you want it gone.
  3. To relocate one, trap it under a cup with a card and release it outside.
  4. If cobwebs keep coming back, reduce outdoor lights that draw insects near windows and doors.

Look-alikes

Black widow (female)A female black widow is glossy jet black with a red hourglass under the belly and usually stays low in dark spots, while the house spider is dull mottled brown-gray with banded legs and no red hourglass.
False widow (Steatoda species)False widows are darker, glossier brown to purple-black with a more oval abdomen; the house spider is lighter and mottled.
Brown widowA brown widow has an orange hourglass underneath and spiky, round egg sacs, while house spider egg sacs are smooth and pear-shaped.

Why it came inside

It lives on and in buildings, building webs in quiet corners, window frames and eaves where lights and walls bring it a steady supply of small insects.

Keep it out

  • Vacuum corners, window frames and ceiling edges regularly, including egg sacs.
  • Seal gaps around windows, doors, pipes and wires with caulk.
  • Keep screens in good repair and add door sweeps and weatherstripping.
  • Use yellow or sodium-vapor style bulbs or keep outdoor lights off to draw fewer insects.

What helps

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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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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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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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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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Sources

  1. University of Florida IFAS (Featured Creatures / EDIS)
  2. Colorado State University, Dept. of Agricultural Biology
  3. UC Statewide IPM Program
  4. University of Minnesota Extension

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