Mothproofing is the practice of protecting natural-fiber clothing and textiles from damage caused by clothes moth larvae. The adult moths you might spot fluttering in your closet aren’t the ones eating your sweaters. It’s their tiny white caterpillars that chew irregular holes through wool, cashmere, silk, fur, and feathers. Understanding this distinction is the key to effective prevention.
Why Moths Target Your Clothes
Clothes moth larvae can digest keratin, a protein found in wool, feathers, fur, hair, leather, and silk. They’ll also feed on lint, dust, dried food residue, and fabrics soiled with body oils or food stains. This means a “clean” closet with dirty clothes in it is still an invitation. Larvae can even feed on blends of natural and synthetic fibers, though they cannot survive on pure synthetics like polyester or nylon.
A female moth doesn’t need much. She lays eggs directly on or near a food source, and when the larvae hatch, they begin feeding immediately. The damage often goes unnoticed until you pull out a favorite sweater and find holes scattered across it. By that point, the larvae may have been feeding for weeks or months.
Cleaning Before Storage
The single most effective mothproofing step is making sure your garments are thoroughly clean before they go into storage. Larvae are drawn to fabrics carrying sweat, skin oils, food stains, or pet hair. Dry cleaning kills moth eggs and larvae already present on the fabric while also removing the moisture and residues that attract them. Machine washing at 120°F (49°C) or above for at least 30 minutes achieves the same thermal kill.
Delicate items that can’t handle heat have another option: deep freezing. Seal the garment in a plastic freezer bag and place it at -18°C (about 0°F) for at least two weeks. This kills adults, eggs, and larvae at every life stage. Some sources suggest shorter durations at slightly warmer freezer temperatures, but two weeks at -18°C is the well-tested benchmark recommended by English Heritage’s conservation research.
Airtight Storage
Once garments are clean, storing them in airtight containers is your best long-term defense. The logic is simple: if adult moths can’t reach the fabric, they can’t lay eggs on it. Any plastic storage box with a tight-fitting lid works. For extra security, seal the edges with packing tape. Vacuum-sealed garment bags are another strong option, and individual items can go into heavy-duty zip-lock bags.
One critical point: if eggs are already on the fabric when you seal it up, you’ve locked the problem inside with your clothes. That’s why the cleaning step comes first. Clean the garment, then seal it. Skipping the first step makes the second one useless.
Mothballs and Their Risks
Traditional mothballs work by slowly converting from a solid into a toxic vapor that kills moths and larvae in an enclosed space. When you smell mothballs, you are inhaling the insecticide. The two active chemicals, naphthalene and paradichlorobenzene, are both classified as pesticides and carry real health risks.
Mothballs are especially dangerous around children and pets. A single mothball can cause serious harm if eaten by a small child, and pets or wildlife may mistake them for food. If someone swallows a mothball, the Poison Control Center (800-222-1222) provides emergency guidance. Mothballs should only ever be used inside sealed containers, never scattered loosely in closets, drawers, or open rooms. Used correctly in an airtight space, they do kill larvae. Used incorrectly, they expose your household to pesticide fumes without being concentrated enough to actually work.
Natural Repellents: Cedar and Lavender
Cedar and lavender are the most popular natural alternatives to chemical mothballs, but they work differently. Neither one kills existing larvae. Instead, they act as repellents that interfere with moth breeding. The volatile oils in cedar and lavender create what researchers describe as “olfactory noise,” masking the pheromones that female moths release to attract males. When males can’t locate females, the breeding cycle breaks down and fewer eggs get laid near your clothes.
Cedar contains a compound called α-cedrene, while lavender is rich in linalool and camphor. Research published in the Journal of Stored Products Research has shown these compounds disrupt the sensory systems of various fabric-feeding insects. But their effectiveness depends entirely on maintenance. Cedar balls or blocks need light sanding with fine sandpaper every season to expose fresh wood and release new oils. In humid climates, the wood pores close up faster, reducing the effective lifespan to about three months between refreshes. Lavender sachets fade even faster and should be gently squeezed every few weeks to crush the dried buds and release more oil.
The takeaway: cedar and lavender are useful as a layer of prevention, particularly for wardrobes and closets you open regularly (where airtight storage isn’t practical). But they won’t solve an active infestation, and they lose potency quickly if you forget about them.
Pheromone Traps for Monitoring
Sticky pheromone traps lure adult male clothes moths using a synthetic version of the female mating scent. The males fly to the trap, get stuck, and can no longer fertilize females. Each trap typically lasts about three months. These are valuable as an early warning system: if you start catching moths, you know you have a problem before the larvae do visible damage.
Pheromone traps have real limitations, though. They only capture males of specific clothes moth species, not females. In a well-established infestation that’s been building over months, trapping alone won’t achieve complete eradication. Think of them as a monitoring tool and a supplement to other methods, not a standalone solution.
Putting It All Together
Effective mothproofing layers multiple strategies. Start by cleaning every garment before seasonal storage, using either heat (washing at 120°F or dry cleaning) or cold (freezing at -18°C for two weeks). Store cleaned items in airtight containers, boxes with tight lids, or vacuum-sealed bags. For closets and drawers you access regularly, use cedar blocks or lavender sachets and maintain them on a seasonal schedule. Place pheromone traps in closets and storage areas so you’ll catch an early sign of moth activity before it becomes a full infestation.
Regular vacuuming of closet floors, baseboards, and corners also removes the lint, hair, and dust that larvae feed on when they can’t reach your clothing. Pay attention to dark, undisturbed areas: the back of a closet, under furniture, or inside garment bags that haven’t been opened in months. Moths thrive in places you don’t look.