Spiders: Identification and Control Guide
By the Clark Pest Entomology Team
Last updated: October 2026
Quick answer: Most spiders you'll find indoors in California and Northwestern Nevada are harmless hunters that eat insects. Only a few are a real medical concern. Use the guides below to identify yours by its legs, body shape and web, then decide whether you need help.
Which spider did you find?
Pick the one that matches what you're looking at.
Brown Widow Spider
The one with banded, striped-looking legs and a spiky egg sac that looks like a tiny cotton ball with points. It's the spider people most often mistake for a black widow.
Black Widow Spider
Glossy black, with a red hourglass underneath. This is the one that actually matters medically, so it's worth learning on sight.
Cellar Spider
The long, thin one almost everybody calls a daddy long legs. Loose tangled webs in basements, garages and ceiling corners.
Brown Recluse Spider
Widely feared and almost never actually here. California has no established populations. Read this one before you assume that's what bit you.
How do these four compare?
| Spider | What you notice first | Where you find it | Medical concern |
|---|
| Brown widow | Striped or banded legs, tan to brown body, spiky egg sac | Patio furniture, mailboxes, meter boxes, fence rails | Lower than a black widow |
| Black widow | Glossy black body, red hourglass underneath | Woodpiles, crawl spaces, garages, under outdoor seating | The main one to know |
| Cellar spider | Very long thin legs, small pale body, messy web | Basements, garages, ceiling corners, under sinks | Not a threat to people |
| Brown recluse | Uniform brown body, violin shape behind the eyes | Not established in California | Rarely relevant here |
Which spiders here are actually dangerous?
Fewer than you'd think. University of California IPM guidance for California (Pest Notes Publication 7442) names the western black widow, Latrodectus hesperus, as the most common harmful spider in the state. A bite can cause anything from a mild reaction to a serious one. Death is very unlikely. Anyone bitten should stay calm and get medical advice.
Two others can bite without it turning into much. The yellow sac spider, Cheiracanthium mildei, usually bites when it gets trapped against skin inside clothing or bedding, and what follows is pain like a bee sting plus some redness and swelling. The red and black jumping spider, Phidippus johnsoni, may bite if you disturb it. California tarantula bites are no worse than a bee sting.
The rest is good news. Spiders eat insects and other arthropods, including plenty of things you'd rather not share a house with. Most species also have mouthparts too small to break human skin, so they couldn't bite you even if they tried.
How do spiders get inside?
Six routes account for most of them, according to UC IPM Pest Notes Publication 7442:
- Foundation cracks and gaps around windows and doors, torn screens included.
- Hitchhiking in on plants, firewood and cardboard boxes.
- Adult males wandering indoors while looking for a mate.
- Wolf spiders pushed out when their outdoor habitat disappears, which happens a lot around new construction.
- Burrow-dwelling females leaving flooded burrows in the rainy season.
- An indoor insect population that gives them a reason to stay.
How do you keep spiders out?
- Seal foundation cracks and the gaps around windows and doors, and fix torn screens.
- Vacuum and sweep on a schedule, especially corners, storage areas and basements. Vacuuming the spider along with its web works fine.
- For a single spider, trap it under a jar, slide paper underneath and put it outside.
- Cut the clutter indoors and out. Store boxes off the floor, away from walls and taped shut. Wear gloves when you clear out storage areas.
- Keep the strip along your foundation clear of trash, leaf litter and heavy plants, and trim vegetation back off the walls.
- Dial back outdoor lighting near doors and windows. The light pulls in insects, and the insects pull in spiders.
- Sweep, hose or vacuum webs off the outside of the building regularly.
Clark's Expert Insight
Spraying is the least useful part of spider control. UC IPM says so plainly: pesticides generally aren't needed for spiders, and sprays only buy temporary quiet unless somebody also handles the housekeeping. What lasts is taking away the reason spiders came. Seal the gaps. Knock down the webs. Clear the clutter and kill the outdoor lights that gather insects against the house. Go after the food supply and the hiding places, and the spiders thin out without much else.
Want the wider picture?
Our field guide Common Spiders in California covers what turns up beyond these four, wolf spiders and yellow sac spiders included, with photos and safety notes.
Frequently Asked Questions About Spiders
What kind of spider has striped legs?
A tan or brown spider with banded, striped-looking legs is usually a brown widow. The egg sac settles it. A brown widow's is covered in pointed spikes, while a black widow's is smooth. Our brown widow spider guide has close-up photos.
Are daddy long legs spiders?
Depends which animal you're looking at, because that nickname gets used for two different ones. Cellar spiders are true spiders, with very long thin legs, a small body and loose tangled webs indoors. Harvestmen aren't spiders at all. They have one fused body section instead of two, and they don't build webs. Our cellar spider guide shows the difference.
Do cellar spiders bite?
They aren't a threat to people. Like most spiders, their jaws are too small to matter, and bites on humans aren't a recognized problem with this species. Indoors they do more good than harm, since they catch other insects.
Are there brown recluse spiders in California?
No. There are no established brown recluse populations in California. University of California IPM reports that individual specimens have turned up after arriving with household furnishings, firewood and vehicles, but nothing breeds here. Most spiders people call a brown recluse in this state turn out to be something else.
Which spiders in California are dangerous?
The western black widow is the one that counts. UC IPM calls it the most common harmful spider in the state, and a bite can run from mild to serious, though death is very unlikely. The yellow sac spider and the red and black jumping spider can bite, usually without much consequence. Nearly every other spider you meet can't bite through human skin.