It is the larvae, not the moths
The adult moth you see flying out of a wardrobe does not eat anything. It has no functioning mouthparts. Its entire job is to lay eggs, and by the time you see it the damage is already being done elsewhere.
The larvae do the eating, and what they eat is keratin: the protein in wool, cashmere, silk, fur and feather. They will not touch cotton or synthetics except incidentally. This is why a moth problem looks so selective, and why it always seems to find the most expensive thing you own.
What draws them
Three things: darkness, stillness, and soiling.
Larvae are drawn strongly to fibres carrying body oils, perspiration, hair products or food residue. A clean cashmere jumper is far less attractive to them than a worn one, and this single fact is most of the prevention available to you.
They also prefer places nothing moves. The back of a wardrobe, under a bed, inside a box that has not been opened since last spring, beneath a heavy piece of furniture standing on a wool rug. These are where infestations establish, not in the clothes you wear every week.
Prevention that works
Clean everything before you store it. Every time, without exception. This is the single most effective thing available and it is not close. Nothing goes into seasonal storage worn.
Disturb and inspect. Once a month, move what is at the back of the wardrobe and look at it, particularly the shoulders and the folds. Infestations are easy to stop early and miserable to stop late.
Store in breathable cotton covers, never plastic. Plastic traps moisture against the fibre, and in a London winter that turns a moth problem into a mould one.
Use acid-free tissue in the folds of anything stored flat.
Vacuum the wardrobe itself, including the corners, the rail and the floor, and empty the cylinder or bag outside the house immediately.
What does not work
Cedar blocks and lavender sachets deter adult moths to a limited degree. They do not kill larvae and they will not clear an established infestation. Cedar also stops working within a year or so as the oils dry out, which almost nobody is told at the point of sale.
They are pleasant and they are not useless. They are simply not a treatment, and any service that presents them as one is selling you scent.
If you already have them
Affected items should be sealed in bags and frozen. Several days at domestic freezer temperature kills every life stage, including the eggs, which is the part most treatments miss.
The wardrobe then needs emptying completely, vacuuming into a sealed bag, and cleaning: rail, corners, underside of shelves, and the skirting behind it if it is a fitted run.
For a serious or recurring infestation, particularly one that has reached carpets or upholstery, the right answer is a specialist pest treatment rather than a cleaner. We will tell you when that point has been reached.
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