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

There's a seasonality to our calls that has nothing to do with the biology of the insect involved, and it's probably the most misleading case in the trade.

Between 1 and 20 October, when morning temperatures settle below 15 °C, people open the storage bag under the bed, the box on top of the wardrobe, the suitcase in the dressing room. They pull out the jumpers, the scarves, the wool coat. And they call. "There are holes everywhere, they appeared this summer."

No. The holes appeared between April and September, a few more each week, while the storage bag stayed closed. The clothes moth has no off-season in a heated flat: what's seasonal is the moment you look.

It's a distinction that changes everything about how you treat the problem — because it means the source of the infestation has had six months to settle somewhere other than the jumper you're holding in your hand.

Interior courtyard of an old residential building seen from below, run-down façades and blue sky

What's really eating your clothes

The moth itself eats nothing at all

First misunderstanding, and it's a big one. The small golden-beige moth you squash against the hallway wall is an adult Tineola bisselliella, the common clothes moth. Its mouthparts are atrophied: it does not feed. It lives one to three weeks, it mates, the female lays 40 to 250 eggs, and it dies.

Squashing the adult gives you legitimate satisfaction but solves strictly nothing — unless it's a female that hasn't laid yet, and you have no way of knowing.

It's the larvae that eat. They are whitish, 1 to 12 mm depending on their stage, with a brown head capsule, and they often live inside a case of silk mixed with the fibres they have grazed themselves — which makes them nearly invisible on tweed or marled wool.

What they digest, and why

The textile moth larva carries in its gut a flora capable of breaking down keratin, the fibrous protein of wool, cashmere, angora, silk, felt, horsehair, fur and feathers. It's a rare ability among insects, and it's exactly why the moth has been a household problem for three thousand years.

A corollary that's often overlooked:

Pure cotton, linen, polyester, viscose and acrylic are not attacked by the clothes moth — unless they are stained with perspiration, sweat, food grease or animal urine. The larva then eats the organic residue and pierces the fabric in the process.

That's why a cotton T-shirt worn for a day and put away unwashed can end up full of holes while a clean jumper right next to it is untouched. It isn't the fabric that attracts them, it's what's on it.

Don't confuse it with the pantry moth

Two entirely distinct insects, two different treatments:

Pheromone traps are not interchangeable: each species has its own molecule. Buying the wrong one gets you a flat zero and leads you to wrongly conclude there's no infestation.

The case-bearing moth, the discreet one

Tinea pellionella, the case-bearing clothes moth, is rarer but harder to spot: its larva carries a rice-grain-shaped silk case that it drags everywhere. If you find something on a skirting board that looks like a small grey spindle about 8 mm long moving slowly, it isn't a speck of dust.

Why the infestation escaped you for six months

They hate light and movement

The entire lifestyle of Tineola bisselliella is organised around avoidance. The female prefers to lay in folds, hems, seams, under collars, in pockets — in other words wherever the fabric never moves and light never reaches.

Practical translation: a garment worn regularly, shaken out, aired and washed is almost never infested. Ninety per cent of the risk is concentrated on textiles that stay motionless for more than three months:

• jumpers and coats in summer storage bags
• wool rugs under a heavy sofa or sideboard
• throws and blankets at the bottom of a chest
• suits and formal dresses worn twice a year
• felt chair pads, rug underlays, old insulation
• sheepskins, taxidermy mounts, antique tapestries

Heating extends the calendar

Outdoors, the moth produces one to two generations a year. In a Paris flat heated to 20–21 °C all year round, it manages three to four. The egg → larva → pupa → adult cycle can complete in 65 to 90 days under favourable conditions, versus more than 200 days in a cold space.

In other words: between the April when you stored your woollens and this October morning when you get them out again, as many as two complete generations may have succeeded one another inside the same storage bag. A single founding female can theoretically produce several thousand descendants over that period.

The real signs, in the order they appear

1. Adults flying low in a room, often in the evening, near a wardrobe. They flee if you turn on the light.
2. A fine, sandy powder at the bottom of the cupboard: this is larval frass, the colour of the fabric eaten.
3. Silky cases stuck in folds, seams, against the wood of the furniture.
4. Whitish cocoons in corners, under a skirting board, behind a rail.
5. The holes. This is the last sign, not the first — and often the only one anyone notices.

If you've reached the holes stage, assume the infestation is at least three to four months old.

Façade of a residential building with colourful balconies and laundry hanging out under a blue sky

The protocol that actually works

It comes down to four steps and none of them is optional. The classic mistake is doing step 3 without step 1, then being surprised when it all starts again in February.

Step 1 — Empty completely, sort, map

Take everything out of the affected piece of furniture. Not just the three suspect jumpers: everything, including the cotton items, including the shoe boxes, including the sleeping bag on the top shelf. Inspect under raking light — a head torch or a small LED torch makes the silk cases far more visible than the ceiling light does.

Sort into three piles:

• Visibly affected textiles (fresh holes, larvae, cases)
• At-risk textiles (clean wool/silk/cashmere but stored in the same space)
• Unaffected textiles (clean synthetics and cotton)

Note where you find the most larvae: that's the source, and that's what needs treating first, not the clothes.

Step 2 — Kill the eggs with cold or heat

Larvae can be seen and removed by washing. The eggs — 0.5 mm, translucent, glued to the fibre — survive a great deal, including a 30 °C wash.

Two reliable methods:

Heat. Wash at 60 °C minimum, for at least 30 minutes. Lethal at every stage. The problem: cashmere, merino and silk don't survive it either. For those pieces, 30 minutes in a tumble dryer at 50–60 °C is often gentler than a hot wash, where the care label allows it.

Cold. Airtight freezer bag, freezer at -18 °C for a minimum of 72 hours. Take it out, let it return to room temperature for 24 hours, then refreeze for 72 hours. The double cycle matters: a single thermal shock lets a fraction of the toughest eggs through. It's the only option for cashmere, a vintage piece or a non-washable textile.

Steam also works, provided there is genuine contact: a handheld steam cleaner passed slowly over the seams, hems and folds of a coat destroys eggs and larvae, where simply smoothing the surface does nothing.

Step 3 — Treat the container, not just the contents

This is the step 8 people out of 10 skip, and it's the one that explains the relapses.

• Vacuum thoroughly inside the furniture: corners, grooves, the back, the undersides of shelves, drawer runners, and above all the skirting board and floor beneath the unit. Pupae leave the textile to transform in a crack.
• Throw the vacuum bag out immediately, outside, in a sealed bag.
• Wash down the surfaces with hot soapy water, then let them dry with the doors open.
• If the furniture is old wood with splits, an aerosol insecticide approved for domestic use applied into the grooves (not onto the textiles) rounds off the job. Respect the ventilation time stated by the manufacturer.
• Don't put anything back until everything is dry and cold.

For wool rugs, the logic is the same: it's the underside and the underlay that harbour the larvae, not the visible surface. An affected rug is treated by turning it over and vacuuming the back and the floor.

Step 4 — Store differently

Going back to the same habits means going back to the same problem next year.

• Nothing dirty goes into storage. Systematic washing or dry cleaning before long-term storage: it's the single most effective measure of the lot.
• Store clean woollens in vacuum storage bags or rigid boxes with a seal. A "breathable" fabric garment bag offers no protection: the female lays right through it.
• If you do use garment bags, choose airtight and opaque ones, and don't leave them unopened for six months.
• Leave space between hanging items, air the wardrobe every month, move heavy furniture once a season.

Repellents: what works, what doesn't

Mothballs are finished

Naphthalene mothballs have been banned from sale to the general public in France since 2008, because of their classification as a suspected carcinogen. If you come across some in a family home, don't handle them with bare hands and dispose of them at a waste collection centre.

Cedar, lavender, patchouli

Red cedarwood contains volatile compounds that repel adults and interfere with egg-laying. Two documented limitations:

1. The effect disappears within 6 to 12 months, as the oils evaporate. A five-year-old cedar block is just a piece of wood. You can revive it by sanding it lightly with fine sandpaper.
2. Cedar does not kill larvae that are already established. It's a repellent, never a cure.

The same logic applies to dried lavender sachets, patchouli or thyme essential oils: a real but weak deterrent effect, needing frequent renewal, useless against an active infestation. A few red cedar blocks spread around a clean wardrobe are a good supplement; on their own, they're not enough.

Pheromone traps: a diagnostic tool

Sticky pads impregnated with sex pheromone attract male Tineola bisselliella. They don't wipe out a population, but they answer two essential questions:

• Do I still have moths after treatment? (zero catches over 4 to 6 weeks = a good sign)
• Where is the source? (put four or five in different rooms and count: the busiest one points to the zone)

A clothes moth pheromone trap more than three months old is saturated and catches nothing more: a classic false negative. Write the date you put it out on the pad with a marker.

Close-up of a brown rat with grey fur, snout and whiskers visible, walking on a concrete surface

Is there a health risk?

Unlike bed bugs or fleas, the clothes moth doesn't bite, transmits no pathogens and is not a recognised disease vector. ANSES does not classify it among pests with a direct health impact.

Two caveats all the same:

• The scales, moults and larval droppings accumulated in a heavily infested textile can add to the allergen load of a home, in the same way as dust and dust mites, in sensitised individuals.
• The harm is mainly financial and heritage-related: a wool coat, a Persian rug, a bespoke suit or textile archives represent considerable sums. That's precisely why museums and conservators treat moths as an absolute priority, with standardised anoxia and freezing protocols.

When to call in a professional

The treatment described above is enough in the vast majority of domestic cases. We step in ourselves when one or more of the following apply:

• Recurrence after two complete, properly executed treatments
• Large area: an entire dressing room, several rooms, a large rug
• Inaccessible source: glued underlay, wool insulation, loft spaces, cracks in old parquet, a valuable piece of furniture that can't be dismantled
• Shared building: moths present in several flats, often via cellars or communal areas where old textiles sit undisturbed
• Valuable textiles requiring anoxia treatment rather than chemicals

In these situations, the work consists first of pinpointing the source precisely — an old bird's nest in a flue, a forgotten rug under a box bed, a stash of rags in a cellar — then treating the surfaces and crevices, never the clothes themselves.

The calendar to remember

The clothes moth is one of the few household pests you can genuinely eradicate without heavy treatment — provided you accept an unpleasant truth: it isn't the jumper that needs treating, it's the wardrobe, and above all the storage habit that made it so welcoming.

Unsure how far an infestation has spread, worried about a valuable rug, dealing with a recurrence that won't end? An on-site assessment tells you in a single visit whether the source is in the textiles, in the furniture or elsewhere in the home. Our quotes are free.