Finding a small insect in the bed is alarming, and most people’s first thought is bed bugs. Quite often it is not. Getting the identification right matters, because the treatment for a carpet beetle problem is completely different from the treatment for bed bugs, and paying for the wrong one wastes money and time.
First, what a bed bug actually looks like
Use these features as your checklist:
- Shape: flat and oval, like a lentil, when unfed. After a meal it swells and becomes longer and rounder.
- Size: adults are about 5 mm long, roughly the size of an apple pip. Young nymphs can be just over 1 mm.
- Colour: reddish brown as adults. Nymphs are pale, almost straw coloured, and go red after feeding.
- Wings: none. Bed bugs cannot fly.
- Movement: they crawl at a steady pace. They do not jump.
- Where: close to where someone sleeps or sits for long periods: seams, piping and labels on the mattress, joints in the bed frame, the headboard, the sofa.
There is a to-scale drawing of an adult, a nymph and an egg on our homepage. If the insect you have found matches on shape, colour and no jumping, treat it as a likely bed bug and keep it for a technician to see.
The common look-alikes
Carpet beetles
The most frequent mix-up we hear about. Adult carpet beetles are small (around 2 to 4 mm), round rather than oval, and usually mottled with brown, white and yellow scales. They can fly and are often found on windowsills in spring. Their larvae, known as “woolly bears”, are hairy, striped and slightly longer than an adult bed bug. Larvae can cause an itchy rash in some people, which adds to the confusion. Look for small holes in wool, felt or carpet edges rather than spots on the mattress.
Bat bugs and bird bugs
These are close relatives of bed bugs and look almost identical to the naked eye. Bat bugs have longer hairs on the area behind the head; you need a magnifier and a good photo to tell them apart. The clue is location: bat bugs and bird bugs live with their hosts, so they show up near a loft with a bat roost or near old bird nests in eaves and chimneys. Treating the bedroom alone will not fix them; the source has to be dealt with, and bats are protected, so that needs specialist advice.
Fleas
Fleas are smaller (1 to 3 mm), dark, narrow from side to side rather than flat from top to bottom, and they jump. If it leaps when you try to catch it, it is not a bed bug. Flea bites tend to be around the ankles and lower legs, and there is usually a pet in the picture.
Booklice
Booklice are tiny (1 to 2 mm), pale and soft-bodied, and turn up in damp spots: on new plaster, around food packets, in stored books. They do not bite. In the pale nymph stage a bed bug can be confused with them, but booklice move in quick, jerky bursts and are found in damp corners, not along mattress seams.
Spider beetles
Spider beetles are round, shiny and reddish brown, with long legs that make them look a little like a tiny spider. They live in stored food and old buildings and feed on dried material, not blood. Their rounded, domed body is the giveaway; a bed bug is flat.
Young cockroaches
Early-stage cockroach nymphs are brown and flattened, which causes confusion. They are longer and narrower than a bed bug, have long antennae, move very fast and are usually found in kitchens and bathrooms near warmth and water. They are rarely found in beds.
Swallow bugs and other true bugs
Some garden bugs come in through windows in late summer. They are often green or patterned and have wings. A winged insect is not a bed bug.
Quick comparison
| Insect | Size | Shape | Jumps or flies? | Usual place |
|---|---|---|---|---|
| Bed bug | about 5 mm adult | flat, oval | neither | mattress seams, bed frame, sofa |
| Carpet beetle adult | 2 to 4 mm | round, mottled | flies | windowsills, carpets |
| Carpet beetle larva | 4 to 5 mm | hairy, striped | neither | carpet edges, wardrobes |
| Bat or bird bug | about 5 mm | flat, oval | neither | near a roost or nest |
| Flea | 1 to 3 mm | narrow, dark | jumps | pet bedding, carpets |
| Booklouse | 1 to 2 mm | soft, pale | neither | damp walls, food cupboards |
| Spider beetle | 2 to 4 mm | round, domed | neither | food stores, old buildings |
Sizes are approximate and drawn from the sources at the end of this page.
How to get a definite answer
- Keep the insect. Put it in a sealed food bag or a small jar. A squashed one is still useful.
- Photograph it next to a ruler or a coin, in good light, from above and from the side.
- Look for other evidence. Bed bugs leave dark spotting along seams and pale shed skins. Our guide to bed bug droppings shows what to look for.
- Use the free identification service. Leeds City Council will identify a sample by email at no charge.
- Book an inspection if you have bites, have found something and still are not sure. A technician can check the bed and the rooms around it in one visit. See bed bug inspection in Leeds.
Bites alone do not settle it. The NHS notes that bites can look like other insect bites or skin conditions, and some people do not react to bed bug bites at all.
If it does turn out to be bed bugs, the form below will put you in touch with a Leeds technician who can inspect and give you a fixed price.