Parasteatoda tepidariorum
Fikret Arda Düzgünses · CC-BYHarmless. Probably the most abundant spider in American houses. It will not bite unless squeezed, and a bite would be trivial.
A common house spider is most often confused with species that are medically significant. If you are trying to rule those out, check these:
Across the whole United States and much of the world. If you have found a small, dull, tangle-web spider indoors, this is the most likely answer.
Window frames, ceiling corners, garages and porches, all year.
It builds an untidy tangle web in a corner and stays in it, often for its whole life. Females hang papery brown egg sacs in the web, which is a reliable identification aid — widows produce smooth or spiky sacs, never these. It is unusually tolerant of other spiders and will build next to them, which is why you often find several webs sharing one window frame.
Nothing needed. It is harmless, it eats flies, and it will not spread through the house. A vacuum clears web and spider together if the cobwebs bother you.
Colour and finish. A house spider is dull mottled brown with faint chevrons and banded legs; a widow is glossy jet black with a red hourglass underneath. The egg sacs differ too: papery brown for the house spider, smooth or spiky for a widow.
No. They will not bite unless genuinely squeezed, and a bite would be trivial. They are among the most useful animals to have indoors.
They tolerate each other unusually well and will build adjacent webs where prey is plentiful, which is why window frames often hold a cluster.
Identify another animal from a photo or return to the Spiders guide.
Last reviewed 2026-07-29. We identify, we don’t diagnose — what we can and can’t tell you.