Your Guide to Bed Bug Identification

Getting the identification right matters because the treatment for bed bugs is quite different from the treatment for fleas, carpet beetles or anything else. This guide goes through what each sign looks like and how to tell bed bugs from the insects most often confused with them.

The Adult Bed Bug

• Size: roughly 4 to 5 millimetres long, like an apple pip or a lentil.
• Shape: flat and oval when hungry; longer, rounder and swollen after feeding.
• Colour: mid to reddish-brown, turning darker and redder after a meal.
• Legs: six, with short antennae at the front.
• Wings: none. They cannot fly and they do not jump.
• Movement: a steady crawl, not fast, and they head for cover when disturbed.

Under a magnifying glass you can see fine bands across the body and short golden hairs. A phone camera zoomed in usually shows enough to compare.

Nymphs, Eggs and Shed Skins

Nymphs

Young bed bugs look like small adults but are paler, from almost clear to straw-coloured. The smallest are about the size of a pinhead and hard to see until they have fed, when a red dot of blood shows through their body.

Eggs

About a millimetre long, pearly white and slightly curved, like a tiny grain of rice. They are glued into crevices, often in small groups, and are easy to mistake for fluff or dust.

Shed skins

Nymphs moult five times, leaving pale, papery, see-through skins shaped exactly like the insect. Finding several of these in a seam is a strong sign of an established problem.

The Marks They Leave

In practice, most people identify bed bugs from these rather than from the insects themselves.

• Dark spotting. Small black or dark brown dots, like marks from a felt-tip pen, which soak into fabric. This is digested blood and it is the most dependable sign.
• Blood smears. Small rusty stains on sheets or pillowcases, often from a bed bug crushed after feeding.
• Clusters. Spotting, skins and eggs grouped together along a seam or joint, because bed bugs gather in the same places.
• A smell. A sweetish, musty odour, but only in a heavy infestation.

What Gets Mistaken for Bed Bugs

• Carpet beetles: the adults are small, round and often patterned; the larvae are hairy and bristly. Neither feeds on blood. See our carpet moth and carpet beetle page.
• Fleas: tiny, dark, narrow from side to side, and they jump. Bites are usually around the ankles. Our flea identification guide explains more.
• Booklice: very small, pale and soft, found in damp spots and around books and packets. Harmless to people.
• Spider beetles: round, shiny and long-legged, usually in cupboards and food stores.
• Bat bugs: almost identical to bed bugs, linked to bats roosting in a roof. The difference needs close inspection.
• Cockroach nymphs: brown and flattened, but faster, with long antennae and found around kitchens.

The insect is the final proof. The spotting is how you usually find it.

How to Check and Collect a Sample

Use a bright torch and a card or old bank card to run along seams. Start at the bed and work outwards: bed bugs stay close to where people sleep. For the full list of places to look, see our post on where bed bugs hide.

• Press clear sticky tape over any insect you find, then stick it to white paper.
• Or drop it into a small sealed bag or jar.
• Take a sharp, close photo next to a coin for scale.
• Note where you found it; that is useful to us.

Do not rely on bites to identify them. Reactions vary so much that our bed bug bites guide treats them as a clue, not proof.

If It Is Bed Bugs

Go straight to what to do if you have a bed bug infestation before anything else. If you cannot tell what you have found, a pest inspection and survey is £120 fixed cost and identifies the pest before you commit to a treatment.

If it is confirmed, our bed bug control service is £220 for the first room, plus £80 for each additional room, with no call-out fee; see the cost guide for how rooms are counted.