Webbing clothes moth larvae are small, cream-colored caterpillars that do all the damage you’ll never see the adult moths cause. The adults don’t eat fabric at all. It’s the larvae, typically less than half an inch long, that chew through your woolens, silks, and furs, sometimes for months before you notice. If you’ve found holes in stored clothing or spotted tiny worms trailing silk threads, these larvae are almost certainly what you’re dealing with.
What They Look Like
The larvae are soft-bodied, worm-like caterpillars with a creamy white body and a darker brown head capsule. They’re small enough to miss on casual inspection, growing to roughly 10 to 12 millimeters before they pupate. What sets webbing clothes moth larvae apart from other fabric pests is their silk. They spin silken tubes and webbing directly onto whatever they’re eating, creating a network of fine threads that can mat into the surface of a garment. You’ll often notice this webbing before you spot the larvae themselves.
This is a useful way to tell them apart from two common lookalikes. Casemaking clothes moth larvae build portable silk cases around themselves, incorporating bits of the fabric they’re consuming, and drag these cases along as they move. Carpet beetle larvae look completely different: they’re covered in tiny hairs or bristles, don’t spin any silk at all, and leave behind shed skins that can resemble living larvae. If you see silken tubes attached to fabric with no portable case, you’re looking at webbing clothes moth larvae.
What They Eat and Why
These larvae feed exclusively on animal fibers: wool, fur, silk, feathers, felt, and leather. All of these contain keratin, a tough structural protein that makes up hair, feathers, and skin. Most insects can’t digest keratin, but webbing clothes moth larvae produce enzymes that break it down, turning your sweaters into a viable food source.
Cotton and synthetic fabrics like polyester and rayon are rarely attacked on their own. The exception is when these fabrics are blended with wool or heavily soiled with food stains and body oils. Sweat, skin cells, and food residue provide extra nutrients that larvae need, which is why a stained cotton shirt stored in a dark closet can still get damaged. Clothes that have been worn but not washed before storage are significantly more attractive to egg-laying adults.
How Damage Shows Up
Webbing clothes moth damage has a distinctive pattern. You’ll find irregular holes in fabric, often concentrated in hidden areas: under collars, along seams, in folds, or wherever the garment was pressed against a surface. The larvae prefer undisturbed, dark spots, so damage tends to appear on items stored for long periods rather than clothes you wear regularly.
Look closely at the damaged area and you’ll likely see fine silk threads, sometimes with tiny fecal pellets (small, sand-grain-sized specks the same color as the fabric being eaten). The webbing can be extensive on heavily infested items, forming a thin mat across the surface. On rugs or carpets, you might notice thinning patches where larvae have grazed the pile down to the backing.
Their Life Cycle and Timeline
Adult webbing clothes moths are small, golden-tan moths about 6 to 7 millimeters long. They avoid light and flutter weakly when disturbed rather than flying toward lamps. Females lay eggs directly on suitable fabric, tucking them into fibers where they’re nearly impossible to see. Within a week or two, larvae hatch and begin feeding.
The larval stage is by far the longest part of the life cycle, and its duration depends heavily on temperature, humidity, and food quality. Under favorable indoor conditions (warm, humid, with plenty of wool or fur), larvae can develop in as little as two months. In cooler or less ideal conditions, the larval stage can stretch to six months or longer. Some sources report larvae surviving for over a year in suboptimal environments, feeding slowly and steadily the entire time. This extended feeding window is what makes them so destructive: by the time you notice damage, larvae may have been at work for months.
How to Kill Larvae in Clothing
Natural repellents won’t solve an active infestation. Cedar, lavender, and similar botanicals work as deterrents to keep adult moths from laying eggs, but they do not kill existing larvae. If you’ve already found holes or webbing, you need direct intervention.
Heat is the most reliable option. Laundering infested items for 20 to 30 minutes in water at least 120°F (about 50°C) kills all life stages, including eggs. For delicate items that can’t be machine washed, a dryer on high heat for 30 minutes achieves the same result. Dry cleaning also kills larvae effectively and is the safest option for structured garments or items with embellishments.
Freezing works but takes longer than most people expect. Place infested items in sealed plastic bags and freeze them at 0°F (-18°C) for at least two weeks. Some entomologists recommend even longer to ensure eggs are killed. The key is sustained, uninterrupted cold: pulling items out and putting them back resets the clock, since larvae can survive brief cold snaps.
Pheromone Traps and Their Limits
Pheromone traps are sticky traps baited with a synthetic version of the scent female moths release to attract males. They’re useful for detecting an infestation and monitoring its severity, but they only catch adult males. They won’t capture females, eggs, or larvae. Think of them as a diagnostic tool, not a solution. If traps are catching moths consistently over several weeks, that tells you larvae are present somewhere nearby and actively developing into adults.
Preventing Reinfestation
Once you’ve dealt with the active larvae, prevention comes down to three principles: cleanliness, storage, and monitoring.
- Clean before storing. Always wash or dry clean wool, silk, and fur items before putting them away for the season. Removing body oils, sweat, and food residue makes fabrics far less attractive to egg-laying moths.
- Use airtight containers. Sealed plastic bins, vacuum-sealed bags, or garment bags with tight zippers physically block adult moths from reaching your clothes. Cedar chests alone aren’t airtight enough unless they’re well-maintained and tightly sealed.
- Add natural repellents as a secondary layer. Cedar blocks and lavender sachets contain compounds that disrupt the ability of moths to detect suitable egg-laying sites. Fresh cedar oil is more effective than old, dried-out wood, so sand or replace cedar products periodically. These repellents make treated areas inhospitable for moths but won’t stop larvae already present.
- Vacuum regularly. Larvae can thrive in lint, pet hair, and dust that accumulates under furniture, along baseboards, and inside closets. Regular vacuuming removes eggs and early-stage larvae before they establish.
Inspect stored woolens every few months, especially during warmer seasons when moth activity peaks. Catching an infestation early, when only a few larvae are present, is the difference between saving a garment and losing it.