Clothes Moths: Why They're Eating Your Sweaters (and Why Cedar Isn't Stopping Them)

Quick answer: The small beige moths in your closet aren’t eating your clothes — their larvae are. Adult clothes moths don’t feed at all; they lay eggs on wool, cashmere, silk, felt and fur, and the grub-like larvae chew the keratin in those fibres for weeks or months before becoming moths. That’s why cedar blocks and mothballs disappoint: by the time you see an adult, damage is already underway inside a folded stack or under a rug. Getting rid of them means killing the larval stage — wash or freeze what can be saved, dry-clean what can’t, vacuum the closet and rug edges hard, and treat the harbourage where eggs survive. An infested wool rug, a stored heirloom, or holes in more than one room is the point to get a professional inspection rather than keep buying traps.

The damage is done by something you’ve probably never seen

Almost everyone who calls us describes the adult: a small, dull, buff-coloured moth about the size of a grain of rice that doesn’t fly toward lights the way other moths do — it scuttles and makes short, erratic hops along a closet wall. People swat it and assume that’s the end of it.

It isn’t. The adult has no functional mouthparts; it cannot eat your sweater. Its two-to-four-week adult life is spent mating and laying eggs — often 40 to 100, cemented onto fibres in a dark, undisturbed spot. The larvae are the feeders: cream-coloured, five to twelve millimetres, dark-headed, hidden inside a silk tube or a portable case made from the fabric they’re eating.

Larvae digest keratin, the protein in animal fibres, which is why the holes are never random. Cotton and polyester come out untouched; the merino beside it is lace. Sweat and body oils make a garment more attractive, so damage lands on the thing you wore once and hung back up rather than the clean item next to it. For the life cycle in detail, see UC IPM’s clothes moth guide and Purdue Extension’s fabric pest publication; our clothes moth library page covers identification.

Why October is when Ontario homeowners notice

Clothes moths live indoors year-round in a heated home — they don’t have a season the way wasps or cluster flies do. What has a season is you.

Wool comes out of storage in October. Bins come down from the attic, sweaters out of the cedar chest, coats off the back rail. That’s when a quiet six-month infestation becomes visible: you unfold the cashmere you packed away in April and find three holes in the shoulder and a dusting of what looks like sand — frass, larval droppings, mixed with shed fibre.

It’s also when people move an area rug for the first time since spring and find a bald patch under the sofa where nobody walks and nobody vacuums. Low-traffic rug margins under heavy furniture are the most common clothes moth site we find across Richmond Hill and Markham.

Webbing or casemaking: tell which one you have

Two species account for nearly all of it in Ontario, and they behave differently enough that identification changes where you look.

Webbing clothes moth. The common one. Larvae spin irregular patches of silk webbing onto the fabric, often with frass stuck in it, and feed underneath. Damage is concentrated — one area grazed to the backing — and the silk mat is still attached when you lift the garment. Adults are uniformly buff-gold, no markings.

Casemaking clothes moth. Less common, more mobile. The larva builds a portable tube of chewed fibre and feeds from inside it, so damage is scattered — small holes across a wide area rather than one bald patch — and you’ll find fibre-coloured cases on shelves and along baseboards. Adults have faint dark wing spots.

Either way, look for larvae and cases, not moths: inside folds, under collars, in seams and cuffs, along the tape edge of wool rugs, in felt piano keys and stored upholstery. Then check the source people miss entirely — a forgotten wool item, a sheepskin, or a bird or rodent nest in a wall void or soffit. A nest full of feathers and fur is prime moth habitat, and it re-seeds the closet no matter how often you clean.

”I have moths in my kitchen too” — that’s a different pest

Worth being blunt: the moths in your pantry are not the moths in your closet.

Pantry moths — Indianmeal moths, mostly — eat grain, flour, cereal, nuts, dried fruit, kibble and birdseed. They’re noticeably larger, with a two-tone wing (pale at the base, coppery-bronze at the tip), and they fly properly across a room toward light. Clothes moths are smaller, plain, and avoid open space. They don’t cross over: a clothes moth won’t infest your flour, and a pantry moth won’t eat your coat.

So one problem doesn’t fix the other: throwing out the bulk bin won’t save the sweaters, and cleaning every closet won’t stop moths coming out of the dog food. Our pantry moth library page covers that side of the split.

Why cedar and mothballs underdeliver

Not “don’t work.” Underdeliver — which is worse, because they create confidence without protection.

Cedar repels at full strength and kills only very young larvae in a sealed space thick with aromatic oil. A chest built in 1950 lost most of that oil decades ago, and the hanging blocks sold today never had enough. Sanding a chest’s interior helps for a while; a block in an open wardrobe does nothing to larvae already feeding.

Mothballs are a registered pesticide, not an air freshener. They sublimate into a vapour that’s lethal only in a sealed container at sustained concentration — which is why you can smell them down the hall, and that smell is the active ingredient escaping to where it does nothing but expose your household. Loose in a closet they’re ineffective against larvae and a real exposure concern around children and pets; Health Canada’s guidance on using pesticides safely applies, and the label doesn’t say “hang in an open closet”.

Pheromone traps catch adult males — useful as a monitor. They don’t reduce the larval population meaningfully, and a trap that keeps filling means you haven’t found the source.

The protocol that actually works

Order matters. Most DIY failures are a correct step done in the wrong sequence, so the larvae simply move.

Empty the closet completely — every item out, so you can see shelves, corners, rail and baseboard.
Sort by what the fabric can take. Washable animal fibre: wash as warm as the garment tolerates, or dry-clean. Non-washable: freeze, sealed in a bag with the air pressed out, at least 72 hours — then thaw and repeat once, since one freeze can miss eggs.
Vacuum hard surfaces aggressively. Shelves, cracks, rail, corners, carpet edges, rug margins under furniture, crevice tool along the tack strip. Empty the vacuum outside immediately — larvae survive in the canister.
Deal with the rug properly. Active damage means both sides vacuumed and the underlay checked; damaged broadloom usually needs professional cleaning or section replacement.
Store clean, store sealed. Moths lay on soiled fibre. Nothing goes into storage unwashed, and seasonal wool belongs in airtight bins — not a breathable cotton bag, which a larva walks through.
Put out monitors for six to eight weeks. Traps still catching at week eight means a source you haven’t found.

Penn State Extension’s factsheet is a good second opinion on the treatment side.

When it’s past the point of a weekend

A few holes in one sweater, caught early, is a laundry-and-vacuum weekend. These aren’t: a wool rug or broadloom with active feeding, where the population rebuilds from a backing no vacuum reaches; holes in more than one room, meaning it’s established in structure rather than a closet; an heirloom, textile collection, piano or stored upholstery; a nest in a soffit, wall or attic; and any multi-unit building, where a neighbour’s untreated unit keeps restarting yours.

Professional treatment starts with an inspection that finds the actual harbourage rather than fogging the closet and hoping, then targeted application of reduced-risk products to the voids, edges and crack-and-crevice points where eggs and larvae survive vacuuming. We treat clothes moths across Mississauga, Etobicoke and Newmarket and throughout our residential service area. Our technicians are employed, licensed and background-checked — never subcontracted — licensed under the Ontario Pesticides Act and registered with the MECP.

The part most people get wrong about fixing it

The economics, plainly: one clothes moth infestation that reaches a wool area rug or a stored wardrobe routinely destroys more value in textiles than years of pest protection costs. And fabric pests are a recurring exposure, not an event — wool keeps coming into the house, storage cycles seasonally, and the harbourage points don’t disappear when the current larvae die.

So the one-time treatment is the entry point; it stops what’s happening now. What keeps it from happening again is year-round protection: scheduled visits that keep treating the perimeter and interior harbourage, catch the next introduction at three larvae instead of three hundred, and bring us back between services instead of issuing a new invoice. That’s why the annual path is our recommended option rather than an upsell — the options are on our plans and pricing page, and the free quote quiz will size the right one in about two minutes. Every service starts with a professional inspection, credited in full when you go ahead with the treatment, and one-time services carry our 60-day guarantee.

Prefer to talk it through? Call (705) 302-1887.

FAQ

Do clothes moths only eat wool? They eat keratin — wool, cashmere, alpaca, mohair, silk, felt, fur, feathers and hair-stuffed furniture. They’ll graze blends for the animal-fibre content and chew through cotton to reach wool underneath, which is why people assume their cotton shirt was eaten when it was only in the way.

Does dry cleaning kill clothes moths? Yes — all life stages, plus it removes the body oils that attract egg-laying. It does nothing about the closet, so clean the space at the same time or the garment gets re-infested.

How long does it take to get rid of them? Six to eight weeks to be confident, not a weekend. One generation runs two to six months indoors, so you need a full cycle of clean conditions with monitors out first.

Are clothes moths a sign my house is dirty? No — worth saying, because people are embarrassed to call. They follow animal fibre, not mess. Spotless homes with good wool rugs get them more often than untidy homes full of polyester.

I threw out the sweater and I’m still seeing moths. Why? The sweater was the casualty, not the source. Keep looking: wool rug margins under furniture, the backs of closets, stored textiles, old nest material in a soffit or wall void.