House Spider Identification — What Spider Is in My House?
Late summer and autumn is 'spider season', when big spiders suddenly sprint across floors and turn up in baths. Upload a photo and our free AI names the spider in seconds and tells you whether it's harmless or one to treat with care.
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How to Identify House Spiders
Check these features before you rely on any single one — the combination is what confirms the ID.
Measure the whole spider including legs against a coin or ruler. Giant house spiders can span 2–3 inches, cellar spiders look large but have a tiny body, and jumping spiders are usually under half an inch.
Extremely long, thread-thin legs on a pea-sized body point to a cellar spider. Thick, hairy legs on a robust body suggest a wolf spider or giant house spider, and short legs on a compact body a jumping spider.
Check the back and underside. A violin shape on the head area suggests a brown recluse, a red hourglass under a glossy black abdomen a black widow, and cream skull-like markings on a bulbous brown abdomen a false widow. Most house spiders have plain or chevron patterns.
Up close, eyes are a reliable family clue. Jumping spiders have two huge forward-facing eyes, wolf spiders two large eyes above a row of small ones, and brown recluses just six eyes in three pairs instead of the usual eight.
Sheet or funnel webs in corners and behind furniture suggest house spiders, messy tangled webs a cellar spider or widow-family spider, and no web at all a wandering hunter like a wolf, jumping, or sac spider.
Spiders sprinting across floors or stuck in the bath in late summer and autumn are usually male house spiders searching for mates. A spider in a dark closet or stored boxes in the south-central US deserves a closer look for brown recluse features.
Common House Spiders and Their Look-Alikes
Giant House Spider
Large, brown, and fast, with long hairy legs and faint chevrons on the abdomen. The spider you see running across the carpet in autumn. Harmless; it rarely bites and its bite isn't medically significant.
Cellar Spider (Daddy Long-Legs)
Tiny body with extremely long, thin legs, hanging in ceiling corners and vibrating its web when disturbed. Harmless to people; the myth that it's highly venomous is false.
Wolf Spider
Hairy, brown or grey, robust hunter that runs along floors and doesn't spin webs. Females carry an egg sac or babies on their back. A bite can hurt but isn't dangerous.
Jumping Spider
Small, compact, often fuzzy, with two big forward-facing eyes, and it hops rather than runs. Curious, harmless, and common on window sills.
American House Spider
Small, brownish, with a rounded abdomen and messy tangle webs in corners, windows, and garages. Related to widows but harmless.
Yellow Sac Spider
Pale yellow to greenish, roams walls and ceilings at night with no web. Can bite if trapped against skin, causing a red, painful bump that usually heals on its own.
False Widow
Bulbous brown-to-purple abdomen with cream markings and reddish legs, common in the UK and Ireland. Its bite is usually like a wasp sting, painful but rarely serious.
Brown Recluse
Uniform tan-brown, with a dark violin shape behind the eyes, six eyes in pairs, and smooth unbanded legs. Found mainly in the south-central US. Its bite can cause a spreading wound, so seek medical care if bitten.
Black Widow
Glossy black with a red hourglass under the abdomen, in undisturbed garages, woodpiles, and outbuildings. Its venom affects the nervous system; seek medical care promptly if bitten.
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Frequently Asked Questions
Sources & References
Our identification guides are researched from the authorities below and reviewed by the IdentifyThis team. AI photo identification is a helpful starting point — for anything involving safety (venomous species, edibility, or medical symptoms), always confirm with a qualified expert before acting.
- CDC — Pest- and health-related guidance
- American Arachnological Society — Spider biology & taxonomy
- BugGuide — Entomology identification community
- UC IPM — University of California Pest Notes
- Smithsonian — Insect & animal biology
Reviewed by the IdentifyThis team · Last updated August 2026