Early signs of bed bugs: how to check a bed in five minutes, and what to do if you find them

Bed bugs are the one household insect where waiting is expensive: a few become hundreds in a couple of months, and every week of delay makes treatment harder. The good news is that they leave evidence that anyone can find with a torch and five minutes, long before the numbers get bad. This guide is about that evidence. It is not about bites. Skin cannot tell you what bit it; the bed can.

The five signs, in the order you usually find them

1. Dark spots. Digested blood: pinhead-sized, black or dark brown, often in clusters along mattress seams, on the box spring, and in the corners of the bed frame. Wipe one with a damp tissue and it smears like ink. This is the most common first sign.
2. Shed skins. Bed bugs moult five times as they grow, leaving pale, translucent, bug-shaped husks behind in the places they hide. They look like empty versions of the insect.
3. Eggs. About 1 mm, white, oval, glued in cracks and seams, often in small groups. Hard to see without a torch held at a low angle.
4. Rust-coloured smears on sheets or pillowcases: a fed bug that was squashed in the night.
5. The insects. Adults are flat, oval, reddish-brown, 4 to 5 mm long, roughly the size and colour of an apple seed, with no wings. Young ones are smaller and paler, almost clear until they have fed. They hide by day and come out at night, so finding one in daylight means looking in the hiding places, not on the sheets.

A sweet, musty smell is often mentioned; it only appears with a large infestation, so do not wait for it.

Where to look, and with what

You need a bright torch (a phone works), an old credit card to run along seams and cracks, and about five minutes. Bed bugs stay close to where people sleep, usually within a couple of metres.

• Mattress: every seam, the piping, the tag, the handles, and any tears. Lift and check the underside edges.
• Box spring or divan base: turn it over if you can; the underside and the corners are the most common home of all.
• Bed frame: joints, screw holes, slats, and the inside of any hollow tubing.
• Headboard: the back and the edges, and the wall behind it, especially if it is mounted.
• Within reach of the bed: bedside tables (drawer joints, underneath), the sofa if anyone naps on it, curtain hems, the edges of the carpet.
• The wall: behind pictures, mirrors, switch plates and loose wallpaper, and along the skirting board.

Run the card edge along each seam and crack and watch what comes out. Look for the dark spotting first; it does not move, so it is the easiest to find.

The hotel check

Bed bugs travel in luggage, and most home infestations start with a trip. Two minutes on arrival:

1. Put your bag in the bathroom or on the luggage rack, not on the bed or carpet.
2. Pull back the sheets at the head of the bed and check the mattress seams and tag with your torch.
3. Look at the edge of the headboard and the bedside table.
4. If you find spotting, skins or an insect, ask for another room on a different floor. Bugs spread through walls to neighbouring rooms.

When you get home from any trip, unpack straight into the washing machine and run the dryer on high for 30 minutes; heat is what kills every stage.

What to do if you find them

• Stay in the room. Moving to the sofa or a spare bed takes the bugs with you and doubles the treatment area.
• Bag textiles at the bed, not across the house, and wash hot, then tumble dry on high for 30 minutes. Things that cannot be washed can go in the dryer alone, or in a sealed bag in a hot car for a day in summer.
• Vacuum seams, cracks and the bed frame, then empty the vacuum into a bag outside.
• Encase the mattress and box spring in bed bug covers, which trap what is inside and make the next inspection easy.
• Call a professional. Whole-room heat treatment or a licensed technician with the right products. Over-the-counter sprays and foggers mostly drive the bugs deeper into walls and into the next room.
• Do not throw the mattress out unless it is falling apart; you will move bugs through the building and buy a new mattress into an untreated room.

What it is not

Three insects get mistaken for bed bugs more than any others:

• Carpet beetle larvae: fuzzy, striped, slow, under furniture and in wardrobes. They eat wool, not people.
• Booklice: pale, soft, 1 mm, on walls and paper in humid rooms. See the white bugs guide.
• Bat bugs and bird bugs: near-identical relatives that live on bats and nesting birds in a loft, and wander into rooms when their hosts leave. The fix is the loft, not the bed.

A spider beetle (round, long-legged, in stored food) or a small cockroach nymph also gets reported as a bed bug; both are rounder and faster.

Front desk note: we will not tell you what bit you, and neither should any app. If the bed is clean after a proper check and the marks continue, the answer is a doctor, not an insecticide.

Found something and not sure? A sharp photo of the insect itself, not the mark on your arm, in the identifier will name it.