Other
The things that turn up indoors and bite, and the far greater number that turn up indoors and cannot. Three of the animals here draw blood; the rest are telling you something about damp.
8 species, each checked against a reference source. Dangerous ones first — that is the question people arrive with.
Medically significant
Everything else
Start with a photograph
Identify this bug 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.
Start with whether it feeds on you
This group has no taxonomy in common — it is arachnids, insects and one crustacean relative — so the useful sorting question is what the animal wants, not what it is related to.
- Eight legs and attached to skin — a tick. The only disease risk in this group.
- Six legs, flat, oval, near the bed — a bed bug. Bites, no disease.
- Flattened side to side and jumps onto ankles — a flea.
- Jumps but is soft, plump and under 2 mm — a springtail. Cannot bite anything.
- Fast, silver, teardrop-shaped, in a bath — a silverfish. Eats paper, not people.
- Pincers at the back end — an earwig. Pinches, does not go in ears.
Most 'bites' in this category are not bites
The commonest reason people arrive here is marks on skin with no insect found, and the honest answer is that several strong candidates never bit anybody. Carpet beetle larval hairs cause a rash routinely attributed to bed bugs. Springtails and silverfish are physically incapable of biting and get blamed constantly. Working backwards from a mark to a species is unreliable in a way that working forwards from a found insect is not — so identify the animal if you can, look for the evidence a real infestation leaves, and treat the bites as the weakest piece of information you have.
Common questions
Something is biting me but I cannot find anything.
Look for evidence rather than the insect: dark smears along mattress seams for bed bugs, black specks that bleed red on wet tissue for fleas. If neither is there, carpet beetle larvae and simple dry-skin irritation are both more likely than an insect nobody can find.
Which of these actually carries disease?
Ticks, meaningfully. Fleas can transmit tapeworm to pets and rarely infections to people. Bed bugs are not established as disease vectors, and nothing else in this group is.
Why do I keep finding bugs in the bathroom?
Because something is staying wet. Silverfish and springtails both need humidity and neither can bite. Fixing the damp removes them more reliably than anything sprayed.
Is it a bed bug or a tick?
Count the legs. Six is a bed bug, eight is a tick. It is the most consequential leg count on this site, because only one of them carries a disease risk.