Clothes Moths Or Carpet Beetles? Read The Damage

Holes in a wool sweater are larval feeding damage, not the work of the adult moth you saw. Two fabric pests do this in Ohio homes, clothes moths and carpet beetles, and both eat animal fiber. Heat ends it: Michigan State University Extension says dry cleaning, or laundering above 120 degrees Fahrenheit for 20 to 30 minutes, kills all stages.

October is when people find the damage, because October is when the wool comes back out. The feeding happened earlier, in the dark. University of Kentucky entomologists describe clothes moth larvae feeding in dark, undisturbed places: closets, chests and boxes where woolens and furs sit for long stretches. Michigan State Extension says infestations often go unnoticed until the damage appears, and that close examination of the item reveals silken webs spun by the larvae. A sweater folded away in April and lifted out this week gave them six quiet months.

Which One Did The Damage?

Silk is the fastest way to separate them. Clothes moth larvae spin it, as loose webbing on the fabric or as a small case the larva drags around with it. Carpet beetle larvae leave shed skins instead, and the empty skins hold their shape well enough that most people count them as insects.

Neither one bites, and neither is a sign of a dirty house. If the thing you found was near a bed instead of a closet, work through carpet beetles versus bed bugs before you go any further, because the fix is completely different.

Why Wool, And Why That Particular Sweater

Keratin is the whole answer. It is the protein in hair, wool, feathers and horn, and University of Kentucky entomologists note that clothes moth larvae digest it and feed exclusively on animal fibers. NC State Extension adds the other half: the larvae cannot digest fibers made from cellulose, such as cotton, rayon or linen. A pure cotton shirt is not food. A wool blend is.

Carpet works the same way. University of Florida Extension states that carpet beetles do not feed on carpet made from synthetic fibers, though blends containing natural fiber can still be damaged. That is why one rug in a room gets chewed and the one beside it never does.

Then there is the part nobody wants to hear. University of Maryland Extension notes that soiled wool is particularly attractive to carpet beetles, and the same holds for clothes moths: sweat, body oil and a spilled drink are nutrition the clean fiber does not supply. The coat you wore all winter and hung up without cleaning is a better target than the one that went to the cleaner first.

What Actually Kills Every Stage

Heat and cold do the work here, not a product sprayed into a closet. Eggs are the stage that survives half measures, so the test for any method is whether the sources say it reaches all of them.

• Launder what can take it. Michigan State University Extension says dry cleaning or thoroughly laundering items in hot water above 120 degrees Fahrenheit for 20 to 30 minutes kills all stages of the insect. If your tap water runs cooler than that, the dryer and the dry cleaner are doing the heavy lifting rather than the wash.
• Freeze what cannot be washed or cleaned. The National Pesticide Information Center, run by Oregon State University under a cooperative agreement with the EPA, suggests sealing items and freezing them for two weeks. Two weeks is the figure that matters, not two days.
• Vacuum the room, not only the garment. University of Maryland Extension recommends thorough vacuuming of carpeting, along baseboards, under furniture and in closets, and then disposing of the vacuum bag outdoors so nothing crawls back out.
• Dry the air. Michigan State notes that keeping indoor humidity low creates an environment that is not suitable for clothes moth development, which is one more reason a damp basement closet is the room that keeps having this problem.
• Clean before storing, every time. The stain is the invitation, so the sweater goes into the box clean, and the box goes somewhere dry and sealed.

Where To Look Before You Buy Anything

The item with holes in it is rarely the only place the larvae are living. Ohio State University Extension's carpet beetle fact sheet, by David J. Shetlar, says the larvae crawl from room to room and live behind baseboards and molding, and in heating system air ducts, dresser drawers, carpets, clothing and furniture. The National Pesticide Information Center suggests a flashlight for the inspection, which is not a small detail when the larvae are easy to miss and the closet has no light in it.

The duct is the one that catches people out. Somebody washes everything in the closet, loses a weekend to it, and the damage starts again from a floor register full of lint and hair that nobody opened. Work through the list below with the flashlight before you spend money on anything:

• Floor registers and cold air returns, especially in bedrooms with carpet.
• Carpet edges where they tuck under the tack strip, and the pile under anything heavy that never moves.
• Wool rug fringe, felt pads under furniture legs, and the underside of upholstered seats.
• Stored down pillows and comforters, old hats, fur trim, taxidermy and piano felt.
• The back corners of drawers and chests where lint and hair collect.

Mothballs, Cedar And Traps

Mothballs are registered to kill clothes moths and carpet beetles inside an enclosed container, and that is the whole scope of the label. The National Pesticide Information Center explains that the label calls for a tightly closed container so the fumes build up where the insects are instead of in living space, and that when you smell mothballs you are inhaling the pesticide. We went through the label and the fumes in what mothballs and ultrasonic repellers really do, and the short version is that a closet with a gap under the door is not a sealed container.

Cedar blocks and lavender sachets come up in every conversation about this. None of the extension sources above lists either one as a control for an active infestation, while all of them list heat. Pheromone traps sold for clothes moths catch adults, and since the larvae are the stage doing the damage, a trap tells you whether there is activity rather than ending it. Use it as a monitor and keep going.

When Is It Worth Having Someone Look?

When the damage comes back after the closet has been emptied, washed and vacuumed, the source is somewhere you have not been: a void, a duct run, under a built in, inside a piece of furniture. When it is a wool rug or an antique that cannot go in a washer, the question becomes what can be done without ruining the item. Both of those are worth a professional set of eyes rather than another weekend of laundry.

A moth flying around the kitchen instead of the closet is usually a different insect altogether, and pantry moths in the kitchen is the post for that one. If you are not sure what you are looking at, our pest identification page and our occasional invaders library will narrow it down.

State Termite & Pest Solutions has worked Northeast Ohio since 1933, out of North Canton and Hartville, across Stark, Summit, Portage, Wayne and Tuscarawas counties. Send a photo of the damage and the insect through our request form for a free estimate, or call 330-494-6199 and tell us which room it started in.