Bed Bug vs Tick
Cimex lectularius vs Ixodes scapularis
Count the legs. Six means a bed bug, eight means a tick. It is the most consequential leg count in this whole subject, because only one of them carries a disease risk — and only one of them means your bedroom has a problem.
The one thing that settles it
Six legs versus eight. A bed bug is an insect and a tick is an arachnid, and nothing about feeding changes that. Even engorged, when both are swollen and unrecognisable, the leg count holds. It is visible on a phone photo at full zoom.
Side by side
| Character | Bed Bug | Tick |
|---|---|---|
| Danger | Take care | Dangerous |
| Legs | Six — an insect | Eight as an adult — an arachnid |
| Where you find it | Not attached to you. In mattress seams, frame joints, headboards | Attached to skin, cemented in place, often in a sheltered fold |
| Disease risk | Not established as a disease vector to people | Real. Lyme disease and several other infections |
| Feeding | A few minutes at night, then back into a crack nearby | Days, attached continuously, swelling as it goes |
| Evidence left behind | Dark smears on seams, shed skins, pale eggs in cracks | None. The tick is the evidence |
| What to do | Confirm with the harbourage evidence, then usually professional treatment | Remove promptly with fine tweezers, note the date, watch for symptoms |
Why they get confused
Both are small, flat, brown and swell up dramatically after feeding on blood, and an engorged one of either is a grey-brown lump that looks nothing like the reference photos. People also meet both in the same context — finding something on skin or in the bed — and reach for the more familiar name. The stakes make the confusion worth resolving properly rather than approximately.
If you still can’t tell
If it was attached to skin and had to be pulled off, treat it as a tick regardless of what it looks like — bed bugs do not attach. Keep it in a sealed bag with the date; that is genuinely useful if symptoms follow, and it lets someone else identify it properly. If it was loose in bedding and not attached, go and look at the mattress seams: bed bugs leave smears and shed skins, and finding those settles it without needing the insect at all.
Common questions
Can bed bugs give you Lyme disease?
No. Bed bugs are not established as vectors for Lyme or any other human disease. Ticks are, which is the whole reason the distinction matters.
It is engorged and I cannot tell. What now?
Legs still work — six versus eight, visible under a phone zoom against white paper. If it came off your skin, assume tick.
Do ticks live in beds?
Not as a population. A tick can be carried in on a person or a pet and end up in bedding, but it does not breed there. Something breeding in the bed is bed bugs.
Full records
Where this was checked
- iNaturalist — Cimex lectularius checked 2026-07-30
- iNaturalist — Ixodes scapularis checked 2026-07-30
Last reviewed 2026-07-30. We identify, we don’t diagnose — what we can and can’t tell you.