Carpet moth damage is one of the few carpet problems that gets worse silently. The adult moth does not eat anything, so by the time you see one fluttering along a skirting board the larvae have usually been feeding for some weeks in a spot you cannot see.
It is almost always a wool problem. The larvae feed on keratin, which is present in wool, silk and animal hair but not in polypropylene or nylon, so synthetic carpets are largely unaffected.
How to recognise the damage
Larval damage looks like thinning rather than a clean hole. The pile becomes sparse in patches, and if you part the fibres you can see the backing through them because the larvae have grazed the pile off close to its base.
Look in the places nobody walks and nobody vacuums, because larvae avoid disturbance and light. That means under sofas and beds, behind long curtains, inside wardrobes, along the edges beside skirting boards and under rugs that never get moved.
- Thin, grazed patches in the pile rather than sharp edged holes.
- Fine sandy debris and tiny silk cases along carpet edges.
- Small pale larvae, a few millimetres long, at the base of the pile.
- Adult moths that run and scuttle rather than fly strongly.
- Damage concentrated under furniture and along skirtings.
Why they choose the spots they do
Larvae want darkness, stillness and a food source that has not been disturbed. Underneath a wardrobe that has not moved in five years is close to ideal. Warm centrally heated houses extend the breeding season, so the old assumption that moths are a summer problem no longer holds.
Soiling makes carpet more attractive to them. Residue from spills, pet accidents and body oils adds nutrients to the wool, which is one reason regularly cleaned carpets suffer less.
What cleaning does and does not do
Thorough professional cleaning removes larvae, eggs, casings and the debris they feed on from the areas it reaches, and it removes the soiling that makes wool more appetising. That is a genuine and useful part of dealing with an infestation.
It is not a substitute for treatment when an infestation is established. Eggs tucked deep into the backing or beneath a fitted unit will not all be reached, and a moth problem generally needs a combination of thorough cleaning, sustained vacuuming and, in serious cases, a pest control treatment. We are honest about that rather than promising cleaning alone will end it.
- Cleaning removes larvae, casings and food residue from accessible areas.
- Moving furniture so the hidden areas are cleaned matters more than the open floor.
- Persistent infestations need pest control alongside cleaning.
- Cleaning after a treatment removes the dead larvae and debris left behind.
The prevention routine
Prevention is mostly about disturbance. Larvae cannot establish where the carpet is regularly moved over, lifted and vacuumed, so a routine that reaches the neglected areas is worth more than any product.
Getting under the furniture even a few times a year makes the biggest single difference, because that is where nearly every infestation we see has started.
- Move furniture and vacuum underneath at least every few months.
- Use the crevice tool along skirting boards and carpet edges every time.
- Lift and vacuum both sides of rugs, especially wool and silk ones.
- Deal with spills and pet accidents promptly so residue does not build.
- Store wool rugs clean, dry and sealed rather than rolled up dusty.
- Check behind full length curtains, a very common overlooked spot.
Wool rugs need extra attention
A wool or silk rug that sits on top of a carpet creates a dark still layer underneath, which is exactly the environment larvae want. Rugs put into storage without being cleaned first are the other classic case, because they go away with soil in them and come out a year later grazed bare in patches.
Professional rug washing before storage is worth doing, and rolling a clean dry rug in breathable material rather than sealed plastic avoids the damp problems that come with the alternative.
When damage is already done
Grazed pile does not grow back. Cleaning will remove the infestation and its debris, and the carpet will look better, but the thin patches remain thin. On a fitted carpet the options are living with it, a patch repair using an offcut, or replacement of the affected room.
On a valuable rug, reweaving by a specialist restorer is possible, and it is worth getting the rug professionally washed first so the restorer is working on clean fibre.