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What Do Bed Bugs Look Like? Yes, You Can See Them With the Naked Eye
Yes, you can see bed bugs with the naked eye. An adult is 4–6 mm long, about the size of an apple seed, with a flat, oval, reddish-brown body. The young stages are the ones people miss: a newly hatched bed bug is about 1 mm long and almost see-through, and the eggs are about the same size.
Bed bugs are also good at hiding. By day they squeeze into mattress seams, the bed frame and small cracks, so many people find the marks they leave long before they see a live bug. For how they live, feed and spread, see our bed bug facts.
So don’t panic if you’ve just found a small bug on your bed. Plenty of tiny insects look like bed bugs and don’t bite. Use the sizes, colours and photos below to check what you’ve found.
Can you see bed bugs with the naked eye?
Yes. Bed bugs are not microscopic: adults are easy to see on a light sheet, and even 1 mm nymphs are visible if you know where to look and use a torch. How easy they are to spot depends on the stage.
| Stage | Size | Colour and shape |
|---|---|---|
| Egg | About 1 mm, a pinhead | Pearly white, like a tiny grain of rice; glued in small clusters |
| Newly hatched nymph | About 1 mm | Almost colourless; a bright red dot after a feed |
| Older nymph | Between 1 mm and adult size | Pale tan, getting browner after each of 5 moults |
| Adult, unfed | 4–6 mm, an apple seed | Flat, oval, light to reddish-brown |
| Adult, just fed | Up to 50% longer | Swollen, rounder and dark red |
| Shed skin | Same size as the bug that left it | Pale, see-through and hollow |
| Dead bug | Any size, often shrivelled | Dark brown to black, often on its back with legs curled |
What does a bed bug look like?
Here’s how each stage of a bed bug looks to the naked eye.
Adult bed bugs
An adult bed bug is about the size and shape of an apple seed: 4–6 mm long, flat and oval, and light to reddish-brown when it hasn’t fed. It has no wings, six legs and two short antennae, and from above you can see fine bands across its body.
After a blood meal, an adult can grow up to 50% longer. Its body swells, turns darker red and looks longer and rounder, like a tiny balloon. You’re most likely to spot adults along mattress seams, on the box spring and behind the headboard, close to where you sleep.
What a bed bug looks like up close
Under a magnifying glass, a bed bug’s body has clear segments covered in short, fine hairs. The head carries a small, dark eye on each side, two antennae and a beak-like mouthpart that folds under the body when it isn’t feeding. The legs are short and sit along the sides, so the bug looks flat and wide rather than leggy.
Bed bug nymphs (baby bed bugs)
Baby bed bugs, called nymphs, are about 1 mm long when they hatch, the size of a pinhead, and almost colourless. They need a blood meal before each of their five moults, and they turn pale tan and then browner as they grow towards adult size.
Straight after feeding, a nymph shows a bright red dot of blood through its pale body, which is the easiest time to spot one. The rest of the time, their size and colour make them easy to miss, which is why an infestation can grow for weeks before anyone notices.
Bed bug eggs
Bed bug eggs are pearly white, about 1 mm long and shaped like a tiny grain of rice. You can see them with the naked eye, but they’re hard to pick out on light fabric, so use a torch and a magnifying glass along seams, joints and cracks.
They’re glued in place in small clusters, so they don’t brush off easily.
Read more: What bed bug eggs look like
Bed bug infestation in your property?
Rely on local specialist for effective bed bug treatment
Are bed bugs visible in all stages of their development?
Yes, but they’re good at staying out of sight. Bed bugs spend the day packed into seams and cracks and come out to feed while you sleep, so you can live with them for weeks without seeing one.
You’re most likely to see a live bed bug:
- at night, if you switch on a torch and check the mattress edges straight away;
- when you strip the bed and look along the seams, piping and labels of the mattress;
- when you move the bed, take off the headboard or empty a bedside drawer;
- in the daytime too, once an infestation is heavy.
Until then, the marks they leave are often easier to find than the bugs. See signs of bed bugs for what to look for, or follow our guide on how to check for bed bugs.
What does a dead bed bug look like?
A bed bug that has been dead for a while looks dry and shrivelled. One that died recently is still reddish-brown, but the body darkens towards black as it dries out. If it fed shortly before dying, it can look larger and darker because of the blood inside.
Dead bed bugs are often found on their backs with their legs curled up. Look in mattress seams, along the bed frame and in cracks near the bed, usually next to shed skins and dark spots. If you find dead bed bugs, there’s a good chance live ones are hiding nearby.
Dead bed bug or shed skin?
The two are easy to mix up, because a nymph leaves its old skin behind in one piece each time it moults.
| Check | Dead bed bug | Shed skin |
|---|---|---|
| Colour | Reddish-brown to black | Pale yellow and see-through |
| Inside | Solid; may hold dark, dried blood | Hollow and empty |
| Shape | Often on its back, legs curled | A papery outline of the whole bug, often split along the back |
| What it means | Bugs are dying, from a treatment or old age | Young bugs are growing, so the infestation is active |
Found a dead bed bug? What it means
One dead bed bug is a warning, not proof the problem is over. Where there’s one, there are usually more, alive and hiding nearby, so check the mattress seams, bed frame and headboard before you decide what to do.
After a professional insecticide treatment, finding dead bed bugs over the next few weeks is normal: the treatment keeps working as hidden bugs cross it and young ones hatch. Seeing live bugs after the final visit is different. Tell your technician, as a follow-up treatment may be needed.
What do bed bugs look like on a mattress?
Start with your bed and mattress: they’re the closest hiding places to you, and bed bugs come out to feed while you’re asleep. Check the mattress and bedding for:
- rusty or reddish smears, left when a bed bug is crushed after feeding;
- tiny dark spots, about the size of a pen dot, that soak into the fabric like ink; these are bed bug droppings.
Then look closely along the seams, piping, folds and labels of the mattress for:
- eggs, empty egg shells and the pale skins nymphs leave when they moult;
- live adult bed bugs and nymphs.
Read more: Bed bugs on a mattress: what to do now
Why bed bug bites aren’t a sure sign of infestation?
Bites are one sign of bed bugs, but they don’t prove you have them, for a few reasons:
- Some people don’t react to bed bug bites at all, so a home can have bed bugs and nobody has marks.
- Flea, mosquito and mite bites can look very similar.
- Fleas usually bite around the ankles and lower legs, while bed bugs bite skin left uncovered in bed, such as the face, neck and arms.
- Itchy skin with no bites can come from a dust mite allergy rather than a biting insect.
A better test is to work through three steps:
- Make sure the marks are bites.
- Find a bug.
- Check that it’s a bed bug, using the sizes and photos above.
If the answer to all three is yes, book a survey. To compare the marks, see bed bug or flea bites and dust mites or bed bugs.
Insects that look like bed bugs
Looks can be deceiving. Several common UK insects are mistaken for bed bugs, so rule them out before you pay for treatment.
Booklice
A booklouse, especially a young one, can look very like a baby bed bug: tiny, pale and wingless. Booklice live in damp spots, on old books and around stored food, and run quickly when disturbed. They feed on mould, not blood, so they don’t bite.
Image by: S. Rae
Fleas
Fleas are mistaken for bed bugs because both bite, but they look quite different. A flea is dark brown, narrow and flattened from side to side, and it jumps; a bed bug is wider, flat from top to bottom, and can only crawl. Cat and dog fleas, the ones most UK homes get, live on pets and in their bedding and bite people mainly around the ankles.
Bat bugs
Bat bugs are close relatives of bed bugs and look almost the same. Telling them apart takes a magnifying glass and an expert eye: bat bugs have longer hairs on the body. Their main host is the bat, so they turn up near roosts in lofts and walls, and they will bite people if the bats leave.
Image by: Gilles San Martin
Still not sure? Catch the insect on clear sticky tape or in a sealed jar and take a sharp photo. Show it to an experienced bed bug exterminator, or call us on 020 3746 2723.
Check also: Bugs that look like bed bugs
