Carpet beetles are small beetles whose larvae eat carpets, clothing, blankets, furs and other fabric made from animal fibre. The larvae cause the damage, not the adults, and they hide in dark, undisturbed places, so the first sign is usually a hole in something stored away or a beetle on a window sill.
What do carpet beetles look like?
The Australian Museum describes the larvae as small hairy grubs, and notes that the larvae are bigger than the adults. The hairs break off when the larvae are handled and can cause an allergic reaction in some people, so use gloves if you are clearing out an affected cupboard.
The adults are small beetles that live mostly outdoors and feed on pollen and nectar from flowering plants. The Museum says finding beetles on window sills in the house may indicate an infestation.
Where do carpet beetles live inside the house?
Eggs are laid in lint accumulations near a food source, in air ducts, in wardrobes, under heavy furniture and behind skirting boards, according to the Australian Museum's carpet beetle page. Each female may lay 40 to 90 eggs, and they hatch in 8 to 15 days.
Larvae avoid light and feed for anything from about 60 days to a year or more, depending on the species, the food available and the temperature. A warm room speeds the cycle up, so heated rooms tend to see the problem sooner than unheated ones.
Before household goods were available, the larvae fed on spider webs, dried animal skins and other dried protein. Typical sources in a house are:
- Wool carpet edges and rugs, particularly under beds and sofas.
- Stored woollen clothing, blankets and feather items.
- Dead insects and old spider webs in ceiling voids, wall cavities and light fittings.
- Pet hair and lint that collects along skirting boards and in air ducts.
- Old bird nests in the roof or eaves, which the Museum lists as an outdoor egg-laying site.
How do you get rid of carpet beetles?
Remove what they are feeding on, then clean the places they hide. The Museum's advice is thorough, frequent vacuuming with attention to carpet edges and the areas covered by furniture. In practice:
- Empty and vacuum wardrobes, drawers and under-bed storage, then seal the vacuum contents in a bag and take it outside.
- Wash woollen and feather items hot where the care label allows, or have them dry-cleaned.
- Move heavy furniture and vacuum the carpet edges and skirtings behind it.
- Clear dead insects and webs from light fittings and window frames.
- Keep vacuuming regularly for several weeks, because larvae can spend 60 days or more feeding.
Why spraying the room does not fix it
The Museum points out that because the adults live mostly outdoors, treatment indoors is ineffective in the long term, as the adult beetles easily re-enter and infest buildings. A spray in the lounge room kills what it touches, but it does not remove the wool rug or the nest material above the ceiling that the larvae are feeding on.
If you find a source that is out of reach, such as old nesting material in the roof void, deal with that first. The same logic applies to bird mites after a nest has been removed, where the nest is the source worth acting on.
When to call a pest controller
Call if the beetles keep coming back after you have cleaned the obvious sources, or if you cannot work out where they are coming from. A general pest treatment covers common household crawling insects and treats internal skirtings and wet areas, plus the eaves, weep holes, window frames, entry points and the perimeter of the house. Carpet beetles are not on that service's list, so call first and describe what you have found, and we will tell you whether it suits the problem before you book. Our guide to preparing for a pest treatment covers what to move and what to leave. You can also get in touch with a photo.
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