The clothes moth does not eat your sweater because it is wool. It eats the fiber because the garment is dirty, dark and undisturbed, and the fiber happens to be made of the protein its larvae need. Wash before you store, seal what you store, and the same wardrobe that lost three sweaters last year will keep the next three.
What the insect actually does
Two species cause almost all domestic damage, and it is the larva rather than the adult moth that eats. Larvae need keratin, which is why wool, cashmere, silk, mohair, feathers and fur are vulnerable while cotton, linen and polyester are not food. They graze along a fold or a shoulder seam, leave webbing and small grains of frass, and prefer the dark corners that nobody moves.
Soil is the attraction. Sweat, skin cells, food marks and hair all supply the moisture and nutrients that let a larva survive on a garment that would otherwise be marginal. Each adult female lays many eggs, and a heated home gives them a long breeding season and several generations between spring and fall. The common clothes moth, Tineola bisselliella, was first described in 1823, and it's the larvae, not the adults, that feed on wool.
What actually works against moths
| Method | Does it work | How to use it |
|---|---|---|
| Washing before storage | Yes. Soil is what attracts them | Wash or dry clean every knit before it goes away |
| A sealed box with a gasket | Yes, if the contents went in clean | Lidded polypropylene, or a case with a seal, not a cotton bag alone |
| Cedar and lavender | Weakly, and only while fresh | Sand the cedar each season. Treat both as scent, not protection |
| Freezing at 0°F (minus 18°C) | Yes, for eggs and larvae | Sealed, for at least 72 hours, and a week to be safe |
| Pheromone traps | Yes, as monitoring | One per wardrobe, replaced every eight weeks. They break the cycle |
| Mothballs with naphthalene | Yes, and they are a health risk | Restricted as consumer biocides in the EU |
| Hanging a sweater on a rail | No, and it stretches the shoulders | Fold everything knitted, always |
The two methods that actually kill them
Freezing and heat are the two reliable ways to kill every life stage. A domestic freezer holds around 0°F (minus 18°C), which is cold enough if the garment stays sealed and in there long enough, and 72 hours is the usual minimum. Heat is faster: thirty minutes in a dryer on high, or a 140°F (60°C) wash, for anything the label will take. Dry cleaning also kills them, which is one reason a secondhand wool coat is worth cleaning before it goes into a wardrobe.
Storing knitwear so it keeps its shape
Fold, never hang. A knitted garment on a hanger carries its own weight from the shoulder seams, which stretch permanently within a season, and a heavy sweater will pull the neckline out of shape as well. Fold along the seams, stack no more than three deep, and put the lighter pieces on top so nothing is crushed at the bottom of a pile.
Take the dry cleaner's plastic off before storage. A plastic bag traps moisture and solvent vapor against the fiber, which is how a clean garment develops a musty smell and, in a damp closet, mildew. Cotton sheets or acid-free tissue are the wrapping that lets wool breathe while still keeping dust off.
Inspect twice a year, in spring when the knitwear goes away and in fall when it comes back. Look along the shoulder seams, the inside of the collar and the cuffs, which is where grazing starts, and shake each piece over a white sheet so the frass and the cast skins are visible. Catching an infestation in its first season is the difference between washing six sweaters and replacing two.
Six things that keep a wardrobe clear
The traps and the boxes do the work. The scent is optional. Prices are shown only where we confirmed them on the brand or retailer page in Oct 2026.
Buy this firstMothPrevention
Pheromone traps, pack of 2
Catches adult males and breaks the breeding cycle. More useful as an alarm: a trap that fills tells you the wardrobe needs a full clear-out rather than another scent block.
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IRIS
Airtight storage box, 60L
The single most effective purchase here, because larvae walk in rather than fly in. Clean contents, a real seal and a dark interior remove everything the insect needs.
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Simple Houseware
Cotton sweater storage bags, set of 3
For knitwear worn often enough that a sealed box is impractical. Breathable rather than airtight, so combine them with a trap and an annual wash.
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Lineco
Acid-free tissue paper, 24 sheets
Acid-free tissue stops the folds of a stored knit marking and absorbs the last of the moisture. Standard tissue paper is acidic, which yellows wool and silk over years.
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Cedar Sense
Cedar blocks and hanging set
Pleasant, and worth it for the wardrobe smell rather than the protection. Sand the surfaces each season, because cedarwood oil fades as the block dries and a stale block does nothing.
Check priceSoak
No-rinse delicate wash, 375ml
Washing is the prevention, and a no-rinse formula makes hand washing six sweaters at the end of a season a single evening rather than a project you postpone.
Check priceIf you already have an infestation
Empty the wardrobe completely, because the larvae are usually in the corners and the seams rather than on the garments. Wash everything vulnerable at 104°F (40°C) or above if the label allows, or dry clean it, or seal and freeze it in batches for a week. Vacuum the empty space thoroughly, including the baseboards and any carpet edges, and put out fresh traps.
Then wait. Traps will keep catching adults for a season or two, and that is normal rather than a sign of failure. The measure of success is that the next fall brings fewer, and the knitwear you stored clean has no new grazing. A professional treatment exists for a severe case involving fitted carpets, and it is rarely needed once the storage itself has been fixed.
