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Signs of Bed Bugs: 7 Signs You Can Spot Before You See a Bug
The most common signs of bed bugs are tiny dark spots along the mattress seams and rusty or red stains on your sheets. Pale shed skins and itchy bites in a line or small group come next. You’ll usually find these marks before you see a live bug, because bed bugs spend the day hidden in seams, joints and cracks close to the bed.
Spotting them early matters: a small infestation is much quicker to clear than one that has spread through the room. Use the list below to check what you’ve found, or start with our step-by-step guide on how to check for bed bugs.
The 7 signs of bed bugs
Some signs prove bed bugs on their own; others only count when you find them together.
| Sign | What it looks like | How sure |
|---|---|---|
| Dark spots | Dots about 1 mm, like a felt-tip pen mark, that soak into fabric | Strong sign |
| Rusty or red stains | Small spots or smears of blood on sheets and pillowcases | Medium: look for spots or skins too |
| Shed skins | Pale, see-through, empty shells in the shape of the bug | Strong sign |
| Eggs and egg shells | Pearly white, about 1 mm, glued in small clusters | Strong sign |
| Live bed bugs | Flat, oval, reddish-brown, 4–6 mm long | Proof |
| Bites | Itchy bumps in a line or small group on skin left uncovered in bed | Weak on its own |
| Musty smell | A sweetish, musty smell in the bedroom | Weak on its own; heavy infestations only |
1. Dark spots (bed bug droppings)
Bed bug droppings are digested blood, so they look like tiny dark brown or black dots, about 1 mm across. On fabric they soak in and spread slightly, like a dot from a felt-tip pen. You’ll find them in clusters along mattress seams and piping, on the bed frame and around the headboard.
To tell droppings from dirt, wipe a spot with a damp cotton bud. Bed bug droppings smear reddish-brown; dust and crumbs don’t.
2. Rusty or red stains on your sheets
Small rusty or red stains on sheets and pillowcases are usually blood. They appear when you roll over and crush a bug that has just fed, or when a bite keeps bleeding a little. On their own they could come from a scratch, so look for dark spots or shed skins nearby before you decide.
3. Shed skins
Young bed bugs shed their skin five times as they grow, and each moult leaves a pale, papery shell in the exact shape of the bug. Shed skins collect in seams, joints and cracks where the bugs hide. Finding several, in different sizes, means bugs are feeding and growing in that spot.
4. Eggs and egg shells
Bed bug eggs are pearly white, about 1 mm long and glued in small clusters in seams, joints and cracks. Empty shells look the same but flatter, with an open end where the young bug hatched. You’ll need a torch and a magnifying glass to see them. Read more about bed bug eggs.
5. Live bed bugs
A live bug is the only sign that proves bed bugs on its own. Adults are flat, oval and reddish-brown, about the size of an apple seed; young ones are smaller and paler. If you catch one, seal it in a bag or jar so a technician can confirm it. Compare it with our photos of what bed bugs look like.
6. Bites
Bed bugs bite skin left uncovered in bed, usually the face, neck, arms and shoulders, and the bites often appear in a line or a small group. Many people don’t react at all, and flea, mite and mosquito bites can look the same, so bites alone don’t prove you have bed bugs. If a bite stays very painful or swollen, or the redness spreads, see your GP. To compare the marks, see bed bug or flea bites.
7. A musty, sweet smell
In a heavy infestation, some people notice a musty, slightly sweet smell in the bedroom, often compared to damp towels or overripe fruit. It comes from chemicals the bugs release, and it gets stronger as numbers grow. A small infestation has no smell you’d notice, so treat a smell as a reason to check, not as proof.
Early signs of bed bugs
In the first weeks the signs are small and easy to miss. The earliest ones are usually:
- a few dark spots along one stretch of mattress piping, near where you sleep;
- one or two pale shed skins in a seam or a corner of the bed frame;
- new bites in a line that weren’t there when you went to bed, especially after a trip or a second-hand buy;
- a tiny pale bug in a seam, easy to mistake for a speck of fluff.
At this stage there’s no smell and no marks on the walls. A quick check of the mattress seams every week or two after a stay away is the easiest way to catch bed bugs early.
Signs of bed bugs on a mattress
The mattress is where most signs show up first, because it’s where bed bugs feed. Look along the piping and seams on all four edges, around buttons and tufts, under labels and handles, and on the underside where the mattress rests on the base. Clusters of dark spots, shed skins and pale eggs in these folds are the clearest signs you’ll find.
If you’ve found them, read bed bugs on a mattress: what to do now.
Bed bug stains on sheets: blood or droppings?
Both leave marks on bedding, but they look different and mean slightly different things.
| Check | Blood stain | Bed bug droppings |
|---|---|---|
| Colour | Red to rusty brown | Dark brown to black |
| Size and shape | Small spots or smears, often uneven | Round dots about 1 mm, often in clusters |
| Damp cotton bud test | Already a smear | Smears reddish-brown |
| What it means | A bug was crushed after feeding, or a bite bled | Bugs are hiding close by |
Both wash out of bedding at 60°C. Marks that keep coming back after a wash mean the bugs are still active.
Signs of bed bugs in other places
As numbers grow, the same signs turn up away from the bed:
- Sofas and chairs: spots and skins along seams, under cushions and inside the frame, especially where someone naps.
- Bed frame and headboard: dark smears on wooden joints, screw holes and the back of the headboard.
- Walls and skirting: dark spots along skirting boards, behind loose wallpaper and pictures, and around plug sockets.
- Clothes and luggage: spots or skins in seams, pockets and the lining of a suitcase after a trip.
Reliable pest control service
Contact us and get assistance from experienced bed bug exterminator.
Do I have bed bugs?
You can be fairly sure you have bed bugs if you find a live bug, or dark spots together with shed skins or eggs in the same seams. Bites or a smell on their own aren’t enough, because other pests and skin problems can cause them.
Bites but no other signs?
It’s common to wake up with bites and find nothing on the mattress, especially early on, or when bugs are hiding in the bed frame or headboard. Check again at night with a torch, look at the frame joints and the furniture next to the bed, and compare your bites with flea and dust mite bites. If a careful check finds nothing, another cause is more likely: see dust mites or bed bugs.
Found signs? What to do next
Don’t move bedding, clothes or furniture into other rooms, and don’t use shop sprays or foggers: both can push bed bugs further into your home. Bag a bug if you can, photograph the spots and skins, and get a technician to confirm what you have. Our bed bugs guide explains the first steps, and you can book bed bug treatment or call us on 020 3746 2723.
