Clothes Moths: Why Pulling Out Your Sweaters in October Reveals a Six-Month-Old Infestation

The call always comes on the same weekend — the one where the morning temperature drops below 12 °C and everyone opens the garment bag they packed away in April. The wording is almost standardised: "I got my sweaters out, there are four holes in my cashmere and a beige moth flew off into the room." Then comes the question that really matters: "When did this happen?"

The answer is unwelcome: somewhere between May and September. An adult moth eats nothing at all — it does not even have functional mouthparts. What made the holes in the sweater was a larva, working slowly, over weeks, in the darkness of a sealed garment bag. The moth that flutters out in October is the end of the story, not the beginning.

A female clothes moth (Tineola bisselliella) lays 100 to 250 eggs directly onto the fibre, and her larvae can feed for 1 to 2 months in warm conditions — and for more than a year if the room is cool. At 25 °C in an unventilated closet, two to three generations follow one another between spring and autumn without a single adult ever being seen.

This article explains how to recognise the two species actually responsible in the Paris region, why your grandmother's mothballs are both banned and useless, the full protocol for treating a wardrobe without throwing everything out, and at what point professional intervention becomes the only option.

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Two species, two damage signatures

Confusing clothes moths with pantry moths is the most common mistake, and it costs weeks. The latter fly around the kitchen and lay eggs in flour or dried fruit. The ones that put holes in sweaters are interested in only one molecule: keratin, the protein found in wool, cashmere, alpaca, mohair, silk, felt, leather, feathers and horsehair.

In practice, three clues are enough:

• Where the holes are. Moths attack folds, armholes, collars and the undersides of sleeves — the areas that are rarely handled. A single hole right in the middle of the back is more often a snag or a chemical burn.
• The silken threads. Larvae spin tunnels of silk mixed with excrement. If you run a finger over the area and the material "pills" into stuck-together filaments, you are dealing with moths.
• Droppings the colour of the garment. The larva digests the dye, so its droppings take on the colour of the wool. A navy sweater yields black grains, an ecru one white grains.

Beware the reverse false positive too: carpet beetles (Anthrenus verbasci, small round beetles 2-3 mm long) cause very similar damage but require different treatment — their larvae are hairy, shaped like a small golden bristly caterpillar, and they are often found on windowsills.

Why October is the month of discovery, not of infestation

The timeline of a textile infestation in the Paris region is almost always the same.

In March and April, the woollens are put away — often unwashed, sometimes merely "aired out". Yet a moth almost never lays eggs on clean wool: it looks for fibres impregnated with sweat, sebum, food residue or animal urine. These nitrogen-rich traces guide the female and feed the larva, which cannot develop properly on keratin alone.

From May to August, the closet heats up. A wardrobe backing onto a south-facing wall, or under the roof, easily reaches 26-28 °C during the day in a Paris flat. Eggs hatch in 4 to 10 days, and the larvae eat, moult and spin in the complete darkness of a storage bag.

In September and October, the adults emerge. They no longer feed, live for two to three weeks, and seek to mate and lay eggs elsewhere. That is when you see them flying heavily along a skirting board — and when you open the garment bag.

The link with thermal insulation is real. Renovated homes in the Paris region — airtight windows, insufficient ventilation, built-in closets with no air circulation — offer stable temperatures, relative humidity of 50-60 % and zero draught. That is exactly the microclimate sought by Tineola bisselliella, a species that has become strictly domestic in northern Europe.

Wardrobe treatment protocol, step by step

Partial treatment achieves nothing: eggs survive wherever you did not look. The rule is simple — treat the entire contents of the affected piece of furniture, plus the two adjacent ones.

1. Empty it completely and sort

Take everything out, item by item, in daylight or with a head torch. Moths hide in turned-up hems, pockets, hoods, woollen belts and socks rolled into balls.

Three piles: affected (holes, cases, visible tunnels), at risk (any animal fibre stored in the same space), not at risk (cotton, linen, pure polyester, unless stained).

2. Apply a thermal shock to the whole "at risk" pile

This is the heart of the treatment, and it is free. Eggs and larvae are killed by temperature:

• Washing at 60 °C minimum for a full cycle: lethal at every life stage. Obviously impossible for cashmere.
• 30 minutes in a hot tumble dryer: very effective, even after a cold wash, because it is the dry heat that kills.
• Freezing at −18 °C for at least 72 hours, in a sealed plastic bag pressed flat so the cold penetrates quickly. This is the solution for delicate materials. Take the bag out and let it return to room temperature without opening it, to avoid condensation on the fibre.
• Professional dry cleaning: effective, and useful for coats, suits and lined garments.

Between the two extremes, running a vertical garment steamer over coats and fitted rugs gets surface temperatures above 90 °C and destroys eggs and larvae in the folds without soaking the item. It is the best-value tool in a home treatment: it also works on curtains and the underside of mattresses.

3. Vacuum and clean the furniture itself

Larvae pupate outside the garment: in shelf grooves, under the closet skirting, behind rails, in drawer corners. Vacuum with a narrow nozzle, working hard on the joints, then dispose of the bag outside the home immediately.

Then wash the surfaces with hot soapy water, dry them, and leave the unit open for 24 hours. A boar bristle garment brush run over each item before it goes back finishes the job: it dislodges eggs stuck to the surface of the fibre that are invisible to the naked eye.

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4. Measure the residual population

Once everything is back in place, check your work. Pheromone traps for clothes moths — sticky cards impregnated with a sex pheromone that attracts males — do not treat the infestation, but they tell you whether it is continuing. Place a trap high up in the closet and check it every two weeks:

• 0 to 1 catch per month: negligible residual population.
• 3 to 10 catches: an active focus persists, some area was missed.
• More than 10: the infestation has settled into the building fabric (glued-down rug, carpet under furniture, sheep's wool insulation, antique seat stuffed with horsehair).

Note: these traps attract only male Tineola bisselliella, and not carpet beetles. No catches combined with ongoing damage points towards beetles.

Mothballs, lavender, cedar: what works and what is just a smell

This point needs to be stated plainly, because it is where repeat infestations are decided.

Naphthalene has been banned from sale to the public in France and the European Union since 2008: classified as a possible carcinogen, it has no place in a wardrobe, still less in a child's bedroom. The paradichlorobenzene used in older cakes and blocks has likewise been withdrawn from domestic use. If you inherit a wardrobe stocked with these balls, air it thoroughly and take them to a waste disposal centre.

Natural repellents do have a real effect, but it is limited and purely repellent: they may deter a female from laying, but they will not kill a larva that is already established.

In the "useful but misunderstood" category, blocks of red cedar wood for wardrobes retain their value on one condition: that they are lightly sanded with abrasive paper every six months to reactivate the release of volatile compounds. An old grey block is purely decorative.

Household pyrethroid-based insecticide treatments do have one targeted use: treating the cracks and crevices of the empty unit, never the garments themselves. In its opinions on biocidal products for domestic use, ANSES regularly points out that broadly dispersing insecticide aerosols in an enclosed space needlessly exposes occupants for little benefit when mechanical cleaning has not been done first. The order of operations matters more than the product.

Storage that prevents a repeat

A treated wardrobe will be reinfested within a season if you fall back into the same habits. Four rules cover the majority of cases.

Nothing dirty goes into storage. This is rule number one, and on its own it solves most problems. A sweater worn three times in March contains enough sweat to attract a female in June. Wash or dry clean systematically before the spring pack-away.

Airtight storage rather than fabric garment bags. "Breathable" non-woven covers are not a barrier: a larva can get through, and a female can lay through the seams. For long-term storage, vacuum storage bags or rigid boxes with a seal provide a genuine barrier — provided you put clean, perfectly dry items in them, otherwise you simply create a mould problem. Cashmere tolerates prolonged compression badly: for precious pieces, choose a rigid box over a vacuum bag.

Rotation and light. A wardrobe that is opened, handled, aired and lit is poor habitat. Twice a year, take everything out and shake it. The items that are never worn — formal dress, inherited coat, wedding suit — are the first to be hit, precisely because nobody ever looks at them.

Inspect what comes in. The second-hand shop, the car boot sale, the Persian rug bought at a flea market and the horsehair-stuffed armchair rescued from a relative are the three classic routes of introduction. Any second-hand item in animal fibre goes through 72 hours in the freezer or via the dry cleaner before it enters the wardrobe. The same applies to wool rugs stored rolled up: a rug rolled up in a cellar is a perfect incubator, and it is often the rug, not the closet, that is the real focus of the infestation.

When to call in a professional

Home treatment is enough in the vast majority of wardrobe cases. It becomes inadequate in four situations:

• The focus is in the building fabric. Glued-down carpet, felt underlay, sheep's wool insulation, tacked-down rugs, floorboards on joists with wool debris accumulated over decades. You cannot freeze a floor.
• Recurrence despite a complete protocol. If pheromone traps are still catching more than five adults a month three months after a full treatment, there is an unidentified source — often a bird's nest in a roller shutter housing or under the roof, continuously supplying feathers and keratin debris.
• High-value items. Textile collections, designer clothing, tapestries, stage costumes: anoxia treatment (oxygen deprivation in a controlled atmosphere), as used by conservator-restorers, is the only reliable non-destructive method.
• Shared buildings and older properties. In a Haussmann-era building, moths travel through service ducts and loft spaces. Treating one flat in isolation fails. An inspection of the common areas, the loft and the shutter housings then becomes essential.

At ProDeratisation, a clothes moth intervention always begins with an identification survey — moth or carpet beetle, focus in the textiles or in the building fabric — before any treatment. The protocols combine targeted treatment of cracks and crevices, high-temperature steam on fixed surfaces and the installation of monitoring traps, with a follow-up check at three weeks to confirm the population has collapsed. Survey and quotation are free throughout the Paris region.

Key takeaways

• The moth you see in October does not eat: the holes were made by larvae between May and September.
• Moths target soiled keratin: storing garments clean is the most effective preventive measure, and the cheapest.
• Every life stage is killed by temperature: 60 °C in the wash, 30 minutes in a hot tumble dryer, or −18 °C for 72 hours.
• Naphthalene is banned, lavender and cedar are repellents only: none of them kills an established larva.
• Pheromone traps measure, they do not treat — but they tell you whether the treatment worked.
• Damage persisting after a full protocol: look for the focus in the building fabric, a rolled-up rug or a bird's nest, not in the closet.

Sources and references: ANSES (opinions and portal on biocidal products for domestic use), INRS (toxicological data sheets on naphthalene and paradichlorobenzene), European regulation restricting naphthalene in consumer products, Muséum national d'Histoire naturelle (identification sheets for Tineola bisselliella and Anthrenus verbasci), preventive textile conservation recommendations from the Centre de recherche sur la conservation des collections.