A tiny brown husk on a windowsill or in a wardrobe can cause a real scare. Many people assume it is a bed bug. Often, however, it is a carpet beetle larva or the skin that one has left behind.

This guide explains how to tell the two apart. It looks at shape, hairs, shed skins, hiding places and the type of damage each one causes.

Why the two get confused

Both are small, brown and found in homes. Both also hide in dark corners and leave small, dry fragments behind. Because of that, a quick glance can fool almost anyone.

Their habits are quite different, though. Bed bugs feed on blood and stay close to where people sleep. Carpet beetle larvae, in contrast, feed on natural fibres and animal products. That one difference helps explain most of the clues below.

Shape and surface

Start with the body. According to UC IPM, carpet beetle larvae are slightly longer than the adults and look like fuzzy or hairy maggots. Some species are banded in alternating light and dark brown. The black carpet beetle larva is shiny, smooth and hard, and can reach about 5/16 of an inch.

Bed bugs look quite different. The NHS says adult bedbugs are around 5mm long and can be dark yellow, red or brown. Their bodies are flat and oval rather than tubular and bristly.

For example, a bed bug looks like a flat seed. A hairy carpet beetle larva looks more like a tiny, tufted caterpillar. If you can see bristles or stripes, you are probably not looking at a bed bug.

Shed skins

Both insects leave shed skins, so this clue needs care. UC IPM describes carpet beetle skins as brown, shell-like and bristly. They are about the size of a grain of salt, and they often sit alongside similar-sized fecal pellets.

Bed bugs also moult as they grow. The CDC lists shed exoskeletons among the signs of bed bugs, along with rust-coloured blood spots. Because they come from a flat, oval insect, they lack the bristly look described above.

As a result, the bristles are the key. A husk covered in tiny hairs points towards a carpet beetle. A smooth shell in a mattress seam points towards a bed bug.

Where you find them

Location is often the clearest clue. UC IPM says carpet beetle larvae live in dark, undisturbed places on fabrics, carpets, furs and animal products. Adults, meanwhile, gather near windows because they are attracted to sunlight.

Bed bugs hide near the bed. The NHS lists bed frames, mattresses, clothing, furniture, behind pictures and under loose wallpaper. The CDC adds that bed bugs tend to live within about 8 feet of the sleeping area.

Therefore, a husk in a wool jumper or under a rug suggests carpet beetles. A bug in a mattress seam suggests bed bugs. Our guide to where bed bugs hide in a bedroom lists the usual hotspots in order.

What they damage

Carpet beetle larvae feed on natural materials. UC IPM says they eat wool, silk, leather, fur and other animal products, but not synthetics. UC IPM says they are more likely to damage a large area on one portion of a garment or carpet, while moth damage more often appears as scattered holes.

Bed bugs do not damage fabric at all. They feed on blood, so their evidence is marks rather than holes. The NHS lists small brown spots on bedding and furniture, and spots of blood from bites or squashed bugs.

So, if you see damage to wool and no bites, carpet beetles or moths are the likelier cause. If you see bites and spots on sheets but no holes, bed bugs are worth ruling out. Our bed bug signs guide shows these marks in more detail.

Bites and skin marks

Here the picture is less certain. The NHS says bedbug bites can be raised and itchy, and often appear in a line or grouped together. The CDC notes that bites may take from one to several days to show, and some people see nothing at all.

The source we used for carpet beetles does not describe biting, so we cannot say more on that point. Instead, it is safer to treat skin marks as a weak clue. Our bites guide explains why bites alone cannot confirm any pest.

Do not rely on a rash to decide. Look for the insect, its skins or its droppings instead. Then compare what you find with the sections above.

Droppings and other marks

Dark specks are common to both pests, which makes them confusing. Carpet beetle fecal pellets are about the size of a grain of salt, according to UC IPM. Bed bug droppings, meanwhile, appear as small brown spots on bedding or furniture, as the NHS describes.

Because both can look like dark dust, a mould patch or a smear of dirt can fool you too. To learn how to separate them, read bed bug faecal spots versus mould.

Eggs add another clue. Bed bug eggs are tiny, white and glued into crevices. See what bed bug eggs look like for where to look.

Other insects to rule out

Carpet beetle larvae are only one of several lookalikes. Pale, tiny insects in damp spots may be booklice instead. Our comparison of bed bugs and booklice covers that case.

The wider methodology page explains how we weigh evidence like this. It also sets out where the facts on this site come from.

Health, rentals and travel

If you are worried about health, the CDC states that bed bugs are not known to spread diseases to people. Our post on whether bed bugs spread disease goes into more detail.

Renters may also wonder who handles a bed bug problem. Our guide to bed bugs in rented homes in the UK explains the basics. Travellers, meanwhile, can read about checking a hotel room for bed bugs.

Getting a clear photograph

A good image makes identification much easier. Place the husk or insect on a plain background with a coin beside it for scale. Take several photos, including one close-up from above and one from the side.

Our guide on how to photograph an insect for identification explains the steps in order. A clear photo helps a professional give a quicker answer.

What to do next

Write down what you found and where. Note whether it was hairy or smooth, flat or tubular, and whether it sat near fabric or near the bed.

Next, run the five-question checker. It works in your browser, so nothing you enter leaves your device. If you have a live specimen or a husk, read our found a bug guide for safe ways to keep it. You can also ask a pest professional to confirm what it is.

Questions and answers

What do carpet beetle larvae look like?

They are small, hairy or bristly grubs, and some are banded in light and dark brown. University pest notes describe them as fuzzy or hairy, which sets them apart from smooth, flat bed bugs.

Are carpet beetle shed skins the same as bed bug skins?

No. Carpet beetle skins are brown, shell-like and bristly, and about the size of a grain of salt. Bed bug skins come from a flat, oval insect and are not described as bristly.

Where do carpet beetle larvae usually live?

Usually in dark, undisturbed places on fabrics, carpets, furs and animal products. Bed bugs, by contrast, hide close to where people sleep.

Sources

We checked the facts in this article against these sources. However, this article supports triage, not diagnosis, so keep any specimen for an expert.