Moths rarely eat pure cotton. Clothes moth larvae target animal-based fibers like wool, silk, cashmere, and fur because they can digest keratin, the protein these materials are made of. Cotton is a plant fiber made of cellulose, which clothes moths lack the digestive tools to break down. However, there are specific situations where moths will damage cotton garments, and understanding those exceptions matters if you’re finding holes in your clothes.
Why Moths Prefer Wool Over Cotton
Clothes moth larvae have evolved a remarkably specialized digestive system built for one job: breaking down animal proteins. Their gut is highly alkaline, creating an extreme environment that softens tough keratin fibers. They then produce specialized enzymes that target the chemical bonds holding keratin together, essentially dissolving what amounts to industrial-strength molecular glue. This converts rigid animal fibers into simple amino acids the larvae can absorb as nutrition.
Cotton doesn’t contain keratin. It’s almost entirely cellulose, a plant-based carbohydrate that clothes moth larvae simply can’t digest. This is why pure, clean cotton clothing sitting in your closet is safe from moth damage. The larvae would starve trying to eat it.
When Moths Do Damage Cotton
There are three situations where cotton isn’t safe:
- Cotton-wool blends. If a fabric blends cotton with wool or another animal fiber, moth larvae will feed on it. They’re eating the wool content, but they’ll chew through cotton fibers along the way.
- Stained or soiled cotton. Food stains, body oils, perspiration, and urine on cotton fabric attract moth larvae. The organic residue gives them something nutritious to eat, and they’ll damage the surrounding cotton in the process. A clean cotton shirt is unappealing; the same shirt with dried sweat around the collar is a target.
- Building pupal cases. Larvae sometimes harvest cotton fibers not as food but as construction material, incorporating them into the silken cases they spin around their bodies during development.
This is why laundering or dry cleaning garments before long-term storage matters so much. Removing body oils and food residue eliminates the very thing that makes cotton vulnerable.
How to Tell if Moths Caused the Damage
If you’re finding holes in cotton clothing, moths may not be the culprit. Several household pests damage fabrics, and each leaves distinct evidence.
Clothes moth larvae leave silken webbing on or near the fabric. Some spin flat mats they crawl beneath while feeding. Others build small tubes incorporating fabric fibers and excrement. If you see fine, web-like material near the damage, that points to moths. One species, the casemaking clothes moth, carries a tiny silken case around its body as it feeds, which you might spot clinging to fabric.
Carpet beetles leave no webbing at all. Instead, you’ll find tiny hairy cast skins (shed as larvae grow) and small sand-like pellets that often match the color of the fabric they’ve been eating. Carpet beetles tend to eat the surface nap off fabric rather than chewing clean holes through it.
Silverfish are actually more likely than moths to damage pure cotton, especially if it’s starched. They feed on starch, glue, and plant-based fibers. Look for irregular holes, notched edges, and yellowish stains. Silverfish rarely bother wool or animal fibers, which is the opposite pattern from moths.
The Two Species to Know
Two moth species cause nearly all household fabric damage. The webbing clothes moth is the more common one, named for the silken mats and tubes its larvae produce while feeding. The casemaking clothes moth is slightly less common and identifiable by the portable silk case its larva drags around. Both species are small, roughly the size of a grain of rice, with pale gold or tan wings. They avoid light and flutter weakly rather than flying in strong, direct paths. If you see a moth boldly circling your kitchen light, that’s a pantry moth or another species entirely.
Adult clothes moths don’t actually eat anything. They don’t even have functional mouthparts. All the damage comes from the larval stage, when the tiny cream-colored caterpillars feed for weeks or months before pupating into adults. By the time you spot an adult moth fluttering near your closet, the damage has already been done by larvae you likely never saw.
Protecting Your Clothes
The single most effective step is cleaning garments before storing them. Washing or dry cleaning removes the body oils, food residues, and perspiration that make fabrics attractive to moth larvae, including cotton fabrics that would otherwise be ignored. This alone eliminates most of the risk.
For long-term storage of wool, silk, or cashmere, sealed containers or garment bags prevent adult moths from reaching the fabric to lay eggs in the first place. Cedar and lavender may repel adult moths to some degree, but they won’t kill larvae already present.
Pheromone traps catch adult male moths using synthetic versions of the scent female moths produce. They’re useful primarily as monitoring tools. If you start catching moths in a trap, that confirms you have an active population, and you can track whether the daily catch rate drops over time as you address the problem. Since traps only capture males, they reduce breeding but won’t eliminate an infestation on their own. Larvae already feeding in your closet will continue their life cycle for weeks or months, eventually pupating into a new generation of adults.
If you discover larvae on a garment, freezing works. Place the item in a sealed plastic bag and leave it in a household freezer for at least 72 hours. Washing in hot water also kills all life stages. For items that can’t be washed or frozen, professional dry cleaning is effective.
Regular vacuuming along closet floors, baseboards, and carpet edges removes stray larvae and eggs before they establish themselves. Pay particular attention to undisturbed areas: the back corners of closets, beneath furniture, and along the edges of rugs where lint and hair accumulate. These quiet, dark spots are exactly where clothes moths prefer to lay their eggs.