Spiders
Only a handful of American spiders can genuinely hurt you, and almost none of the ones people panic about are among them. These pages lead with the danger answer and then show you what the animal was mistaken for.
16 species, each checked against a reference source. Dangerous ones first — that is the question people arrive with.
Medically significant
Everything else
- Banana SpiderTrichonephila clavipesHarmless
- Barn Funnel WeaverTegenaria domesticaHarmless
- Carolina Wolf SpiderHogna carolinensisHarmless
- Cellar SpiderPholcus phalangioidesHarmless
- Common House SpiderParasteatoda tepidariorumHarmless
- False WidowSteatoda grossaTake care
- Hobo SpiderEratigena agrestisTake care
- Jumping SpiderPhidippus audaxHarmless
- Southern House SpiderKukulcania hibernalisHarmless
- Spider CricketDiestrammena asynamoraHarmless
- Woodlouse SpiderDysdera crocataTake care
- Yellow Garden SpiderArgiope aurantiaHarmless
- Yellow Sac SpiderCheiracanthium inclusumTake care
Start with a photograph
Identify a spider from a photo. The result includes confidence, common lookalikes and a plain safety assessment; read its accuracy and limits before treating a low-evidence photo as definitive.
Found a mark but not the animal? See why a bite cannot identify the bug.
Guides for bugs described by appearance
How to know you have a spider at all
Before species, settle the group. A surprising share of “spider” sightings are something else entirely, and getting the group wrong is how every serious misidentification starts.
- Eight legs. Six means an insect — including the long-legged spider cricket, which is a cricket.
- Two body sections joined by a narrow waist, not three.
- No antennae. Nothing with antennae is a spider.
- No wings, ever. A winged thing is an insect however it is shaped.
- Harvestmen (daddy long legs of the field) have one oval body and no waist — not spiders, and they have no venom at all.
The brown spider problem
Most difficult identifications in this group come down to one thing: a nondescript brown spider, usually a mature male, photographed from above. Recluses, funnel weavers, house spiders and crevice weavers all look broadly alike from that angle, and the character that separates them — the arrangement of the eyes — is almost never visible. When a photo cannot settle it, we say so rather than guessing, because a confident wrong answer here is the one failure that actually hurts somebody.
Common questions
How many spiders in the US are actually dangerous?
Very few. Widows and recluses are the two groups that matter medically. Everything else you are likely to meet indoors ranges from harmless to briefly painful.
How do I tell a spider bite from something else?
Usually you cannot, unless you saw the spider. Bites are far less often spiders than the internet suggests, and bacterial infections in particular look very similar. Identify the animal, not the mark.
Should I kill spiders I find indoors?
There is rarely a reason to. Most house spiders are eating the insects you would rather not have, and cellar spiders eat other spiders. Glass and card puts anything outside in a few seconds.
Why do I suddenly have spiders in autumn?
Mature males wander looking for mates in late summer and autumn. The population has not exploded — the males have simply started walking around, and that is when people notice them.