How we rate danger

Every species page opens with one of three ratings, before anything else.

Get advice

A bite, sting or attached tick can need medical care or can spread serious disease. These pages show Poison Help, 1-800-222-1222, at the top. Examples: widow spiders, the brown recluse, the Arizona bark scorpion and disease-carrying ticks.

Be careful

It can bite, sting, feed on people or spread germs and allergens. That is usually mild, but it can be serious for people with allergies, young children or other groups named on the page. Examples: wasps, fire ants, bed bugs, mosquitoes and cockroaches.

Harmless

No meaningful threat to people. It may still damage food, fabric or wood, and the page says how to keep it out.

How a rating is decided

• Every rating needs at least two published sources that agree, and at least one must be from the CDC, another government agency, or a university extension service.
• When sources disagree, we use the more cautious rating and say so.
• Every Get advice rating was checked a second time by a separate reviewer and approved before publishing.
• We never tell you what bit you. If you are worried about a bite, call Poison Help or a doctor.

Where the state lists come from

State lists use research-grade sighting records from iNaturalist. For dangerous species we also use published range maps from the CDC, the USDA and university extension services, and we mark sightings outside the known range as "recorded, not established".