The Larva Is What Eats — Not the Moth

The fact

The Adult Has No Interest in Your Carpet

The damage is done entirely by the larva: a cream grub, a few millimetres long, living down in the pile or inside a garment. It is the only stage with working mouthparts for the job.

The adult moth exists to reproduce. In the common clothes moth it does not feed at all - it emerges with everything it needs, lives two to four weeks, mates, lays forty or fifty eggs and dies. It could not eat your jumper if it wanted to.

So the moth you see is not the problem. It is the receipt.

What follows

Why a Fly Spray Achieves Nothing

An aerosol emptied into the air kills adults in the air. That removes some of the next generation's parents, which sounds useful until you count: the eggs those adults came from were laid weeks or months ago and most of them are already larvae, down in the pile where nothing airborne reaches.

The same logic explains a whole category of disappointment. A plug-in, a scented sachet, a spray round the skirting on a Saturday afternoon - all aimed at the flying stage, all leaving the feeding stage untouched, and all followed by a fresh bald patch in the autumn.

It also explains why the damage seems to appear from nowhere. By the time an adult is flying, it has been eating in that room for weeks. The visible moth is the end of the story, not the beginning.

The timings

Weeks in a Warm House, the Best Part of a Year in a Cold One

Eggs hatch in something like four to ten days in a warm room. The larval stage is the variable one and it is variable by a lot: a few weeks where it is warm and the food is good, and many months - even most of a year - where it is cold or the food is poor. Then a pupal stage in a crevice, and the adult for two to four weeks.

The practical consequence of that spread is the one that catches people out. At any given moment in an infested room, all four stages are present, and they are not synchronised. There is no point in the year when the room contains only one stage, which is why a single visit rarely finishes it.

Central heating changed this. The old pattern of one or two generations a year with a winter pause does not apply to a house that sits at twenty degrees from October to April. It just keeps going.

What a treatment has to do instead

Reach the Floor, Then Come Back

Three things fall out of the biology, and they are exactly what a proper treatment consists of.

Physical removal first. Vacuuming the edges, the gripper and under the furniture takes out eggs, larvae and cases directly. It is the only part of the job that acts on the egg stage at all.

A residual where they live. Product into the pile, the perimeter and the undisturbed areas - not into the air. It has to still be there when the next larvae start moving about.

A second visit. Timed so that eggs which were beyond reach the first time have hatched into larvae that are not. That is not an upsell; it is the only way to cover a stage that nothing reliably kills.

If somebody offers to solve a moth problem in one visit with a spray and no vacuuming, the biology says otherwise.

Short answers

Carpet Moth Questions

Going further

Carpet Moth Guides