The short answer
Carpet beetle larvae are small, bristly, banded brown grubs, often called woolly bears, that eat wool, fur, feathers and silk. They leave clean round holes with no webbing, hide in carpet edges, under furniture and near old bird nests, and are cleared by finding the source, vacuuming thoroughly, freezing or sealing affected items and, if they persist, a professional treatment.
If you have found a tiny hairy grub on the carpet, in an airing cupboard or inside a drawer of jumpers, it is very likely a carpet beetle larva. In London these are common enough that most people who find one have never heard of them, and many assume they have moths.
What carpet beetle larvae look like
The larva most Londoners find is the young of the varied carpet beetle. The Natural History Museum describes it as 4 to 4.5 mm long and covered in hairs, with tufts of backward-pointing hairs at the tail end, which is why people call them woolly bears. They are banded in shades of brown and move slowly.
Two other species turn up in British homes:
- The two-spot carpet beetle, or fur beetle. Its larva grows to about 6.5 mm, torpedo-shaped, golden yellow to brown, with two long orange tufts at the rear.
- The brown carpet beetle, sometimes called the vodka beetle. Its larva reaches about 8 mm, bronze-brown on top, with two brush-like tufts. It arrived in Britain in the 1970s and relies on central heating in northern Europe.
Under a hand lens the difference from a clothes moth larva is plain. Moth larvae are smooth, shiny and creamy white with a dark head. Woolly bears are bristly all over.
What the adults look like
The adult varied carpet beetle is small and round, 1.5 to 3.5 mm, with a mottled pattern of white, orange and black. You are most likely to see them on windowsills in spring and early summer, because adults head for the light to get outside and feed on pollen from flowers. A few beetles on a sunny sill is often the first clue that larvae are living somewhere in the room.
What they eat
The larvae need keratin, the protein in animal fibres, so they eat:
- wool carpets, rugs and blankets
- knitwear, felt, tweed and tailoring
- feathers in pillows, duvets and old cushions
- fur, leather and hide
- silk, and the dust and fluff that builds up from all of these
They also feed on dead insects and on the debris in old bird nests. The Natural History Museum notes the varied carpet beetle is the only British species of its group that also turns up in stored food.
How the damage differs from moths
Carpet beetle larvae leave small, clean, round holes with no silk webbing around them, often through several layers of a folded garment. You will also find their cast skins, the empty papery shells left each time a larva moults, and a fine powdery dust of droppings.
Moth larvae, by contrast, spin silk webbing or cases and leave grittier droppings. If you find webbing, read our guide to moth larvae instead.
Where they hide in London homes
Woolly bears avoid light and keep to places where fluff collects:
- the edges of fitted carpet and under the gripper rods
- gaps between floorboards, especially in Victorian and Edwardian houses
- under beds, sofas and heavy furniture that never moves
- airing cupboards, drawers of stored woollens and blanket boxes
- lofts and eaves, around old bird or wasp nests
- chimney breasts, where nests and dead insects build up
Many London infestations start in the roof. Pigeons and sparrows nest in eaves and parapets, beetles breed on the old nest material, and the larvae work their way down into the bedrooms below.
How long they stay as larvae
This is why carpet beetles are slow to clear. Indoors the varied carpet beetle may take about a year to complete its life cycle, and the larvae need temperatures of roughly 15 to 25°C to develop, which a heated London home provides. The fur beetle’s cycle can run from six months to three years. A single round of cleaning rarely catches every larva.
How to get rid of carpet beetle larvae
Find the source
Check the loft, eaves and chimneys for old nests and dead insects and have them removed. Without this step larvae keep arriving from above.
Vacuum hard and often
Vacuum carpet edges, floorboard gaps, under furniture and inside drawers and wardrobes. Use the crevice tool. Empty the vacuum into a sealed bag and put it in an outside bin straight away.
Treat affected items
The Natural History Museum suggests a deep freezer at -18°C for affected items, and storing clean woollens in sealed polythene bags. Wash what can take a hot wash.
Call a specialist if they keep appearing
If you still find larvae after a few weeks of this, a professional treatment of the carpet edges, gaps and voids, usually over two visits, is the next step. In London that typically costs £200 to £300; see our carpet beetle treatment page and the price calculator for more.
Can they harm people?
Carpet beetles do not bite. The larval hairs can, though, irritate skin in some people, producing itchy red bumps that are easy to mistake for bites, as a 2024 review in the journal Cutis explains. Our guide to carpet beetle bites covers what that rash looks like.
If woolly bears keep turning up in your home, ask us for a specialist and we will find one who covers your postcode.