Clothes moth caterpillars are small, cream-colored larvae, typically less than half an inch long, and they are the only stage of the moth’s life cycle that damages your belongings. Adult clothes moths don’t eat fabric at all. If you’ve found tiny worms on a wool sweater or noticed irregular holes in stored garments, larvae are almost certainly responsible.
What They Look Like
Two species cause most clothing damage worldwide: the webbing clothes moth and the casemaking clothes moth. Both produce pale, whitish caterpillars with darker heads, but their behavior makes them easy to tell apart.
Webbing clothes moth larvae spin silken tubes or patches of webbing as they crawl across the surface of whatever they’re eating. You’ll see a network of fine silk threads clinging to the fabric, along with tiny fecal pellets. The caterpillar itself moves freely, ducking under its webbing for cover.
Casemaking clothes moth larvae take a different approach. Each one builds a small, open-ended tubular case out of silk and bits of the material it’s feeding on. The larva drags this portable shelter everywhere it goes, pulling it along like a sleeping bag. Because the case incorporates fibers from the fabric, it often matches the color of the garment, making it surprisingly hard to spot on a dark wool coat or a tan carpet.
What They Eat and How
Clothes moth caterpillars feed on keratin, the tough protein found in wool, fur, feathers, silk, and hair. Keratin is notoriously difficult to break down. Its tightly coiled molecular structure resists most digestive enzymes, which is why so few animals can eat it. Clothes moth larvae produce unusually high levels of specialized digestive enzymes, primarily in the trypsin and chymotrypsin family, that can dismantle keratin’s structure. This ability appears to be the larvae’s own biology rather than the work of gut bacteria.
Synthetic fabrics like polyester and nylon are safe from these caterpillars because they contain no keratin. But blended fabrics (say, a wool-polyester mix) can still be damaged: larvae chew through synthetic fibers to reach the natural ones. Soiled clothing is especially attractive. Sweat, food stains, and body oils provide extra nutrients and moisture, so a dirty wool sweater stored in a dark closet is essentially an invitation.
Signs of an Active Infestation
The damage clothes moth caterpillars leave behind is distinctive. Rather than clean-cut holes, you’ll find threadbare patches where fibers have been grazed away at the base. These spots often appear along seams, inside folds, and in areas that stay dark and undisturbed, like the underside of a collar or the back of a rug near a wall.
Other telltale signs include:
- Silken webbing or tubes on the fabric surface (webbing clothes moth)
- Small portable cases made of fabric fibers, roughly the size of a grain of rice (casemaking clothes moth)
- Tiny fecal pellets that look like fine sand scattered near the damaged area
- Shed larval skins left behind after molting
You may also notice small, golden-tan adult moths (about a quarter-inch long) fluttering weakly near closets or in dim corners. Unlike pantry moths, clothes moths avoid light and tend to scurry or hop rather than fly strongly. Spotting adults confirms that larvae are somewhere nearby, even if you haven’t found them yet.
How Long the Larval Stage Lasts
The caterpillar stage is by far the longest part of a clothes moth’s life. Under favorable conditions (warm temperatures, moderate humidity, and plenty of food), larvae typically feed for several weeks before pupating. In cooler or drier environments, development slows dramatically, and the larval stage can stretch to several months or even over a year. This is why infestations in unheated attics or storage units can persist quietly for a long time before anyone notices damage.
Low humidity discourages clothes moth development. Buildings that stay dry indoors naturally have fewer problems, while damp basements and humid closets provide the moisture larvae need to thrive.
Killing Larvae With Heat or Cold
Temperature is the most reliable way to kill clothes moth caterpillars at every life stage, including eggs hidden in fabric. You have three practical options:
- Hot washing: Launder infested items for 20 to 30 minutes in water at least 120°F. This kills eggs, larvae, and adults. It’s the most effective single method for washable garments.
- Dry heat: Place the item in an oven at over 120°F for at least 30 minutes. This works for items that can tolerate heat but not water, like some upholstery pieces.
- Freezing: Seal the item in a plastic bag and place it in a freezer below 18°F for at least 72 hours. Freezing is useful for delicate items like fur, vintage textiles, or items with embellishments that can’t be washed or heated.
Dry cleaning also kills all life stages and is the best choice for structured garments like suits and coats that shouldn’t be machine-washed.
Cleaning the Space
Killing larvae on individual garments solves only part of the problem. Eggs and larvae can be hiding in carpet edges, closet cracks, lint accumulations behind furniture, and the seams of upholstered chairs. A thorough vacuum is the single most important step. Pay close attention to closet floors, baseboards, shelf edges, and any crevice where lint and hair collect. Dispose of the vacuum bag or empty the canister immediately afterward, because it will contain live eggs and larvae.
Brushing garments outdoors in direct sunlight is also surprisingly effective. Larvae avoid bright light and will drop off fabric when they can’t find cover. Brushing along seams, inside pockets, and within folds crushes eggs and dislodges larvae that would otherwise stay hidden.
Do Cedar and Lavender Actually Work?
Cedar and lavender are popular natural deterrents, but their effectiveness is limited. The volatile oils in cedar (primarily a compound called alpha-cedrene) and lavender (linalool) work mainly by masking the pheromones female moths release to attract males. This “olfactory noise” can disrupt the breeding cycle by making it harder for males to find mates, which in theory prevents new eggs from being laid in the treated area.
The critical limitation: cedar and lavender do not kill existing larvae. They are repellents, not insecticides. If you already have caterpillars feeding on your clothes, sachets and cedar blocks will not stop them. These products work best as a preventive layer in closets and storage containers that are already confirmed moth-free. Cedar also loses potency over time as its oils evaporate, so blocks and rings need occasional sanding or refreshing with cedar oil to remain effective.
Mothballs and Insecticide Options
Traditional mothballs and moth crystals contain paradichlorobenzene, which evaporates into a vapor that slowly kills insects. The catch is that these vapors only reach lethal concentration inside an airtight container. In an open closet, mothballs merely act as a weak repellent, and larvae already on your clothes will keep feeding. If you use them, seal treated garments inside a zippered garment bag or a tightly closed storage bin.
Keep mothballs away from direct contact with plastic hangers, buttons, or garment bags, as the chemical can soften and melt plastic into the fabric.
Spray insecticides designed for clothes moths typically contain pyrethrins, which provide a fast knockdown. These can be applied directly to fabrics in most cases, but check the label for any fabric restrictions. For cracks and crevices in closets and baseboards where larvae hide, dust formulations containing pyrethroids can be worked into gaps that sprays can’t reach.
Preventing Reinfestation
The most effective long-term prevention combines cleanliness, proper storage, and monitoring. Clothes moth caterpillars thrive on neglect: garments stored dirty in dark, undisturbed spaces for months at a time are the highest-risk items.
Before storing anything made of wool, silk, fur, cashmere, or feathers, wash or dry-clean it. Even if a garment looks clean, invisible skin oils and perspiration attract egg-laying moths. If you can’t wash an item, freeze it for 72 hours before storing it.
For long-term storage, moth-proof garment bags with sealed zippers provide a physical barrier that prevents adult moths from reaching your clothes. Vacuum-sealed bags work too, as long as the garments inside are confirmed pest-free before sealing. Standard cardboard boxes and plastic bins with loose-fitting lids are generally not airtight enough to keep moths out. Pairing sealed storage with a cedar or lavender sachet inside adds an extra deterrent layer.
Pheromone traps placed in closets and storage areas catch adult male moths, which both alerts you to a new infestation early and removes males from the breeding cycle. These traps are available for both webbing and casemaking clothes moths and are a simple, low-maintenance way to keep tabs on whether your prevention efforts are working.