Extension Educator, Horticulture
It's cold. You dig out your favorite wool sweater but you don't remember purchasing the ventilated version. So what made all the extra holes? Was there a mad button holer running amuck in your attic?
In the natural world your wool sweater is considered a discarded sheep skin so nature sends in the clean-up crew of various beetles to dispose of the refuse. To them your woolens say smorgasbord.
Dermestid beetles include various species of carpet beetles and larder beetles. They feed on organic fibers and grains including wool, fur, feathers, hair, flour, beans, animal dandruff, dead insects, leather, silk, dog and cat food, bird seed, powdered milk, dried meat, animal trophies, dead rodents in wall voids, book bindings, cotton and linen. They will even feed on the felts on hammers of old pianos. So if your piano sounds funny, check to see if you have an accompaniment of tone deaf beetles. They will also feed on wall hangings, rugs and insect collections. Carpet beetles are the scourge of museums. They do not feed on synthetic fibers, so your polyester leisure suit is safe. They will, however, feed on blends of wool and synthetics.
Adult beetles vary from 1/8 inch to ¼ inch long. They have typical roundish beetle bodies of black or brown with short antennae. Some species have markings of yellow or white. Don't confuse carpet beetles with Asian multicolored lady beetles that are orange to brown with dark spots and do not feed on clothing. Carpet beetles develop from eggs to become larvae, form a pupa then become adults. Like most families it's the youngsters that do the most damage. Larvae resemble little furry cigars about ¼ inch long with white bodies covered with long brown hairs. Larvae prefer dark secluded places to feed. Adult beetles feed on flower nectar and pollen and are attracted to night lights. They may fly into homes in May and June.
Some moth caterpillars also feed on clothing. With clothes moths you will see the young hairless caterpillars or cocoons. Carpet beetle larvae have the characteristic brown hairs and will also leave shell-like skins covered in bristles as they grow and molt.
Managing carpet beetles requires several approaches. First good sanitation is important to remove extraneous food sources. Vacuum regularly to remove lint, hair and other debris. Be sure to vacuum furniture, carpets along baseboards, under heavy furniture and in closets. After vacuuming areas that are known to be infested, change the vacuum cleaner bag immediately. Clothing should always be cleaned thoroughly before storing. Perspiration and food stains attract carpet beetles. Thorough laundering in hot water or dry cleaning will kill all stages of the beetles. Freezing items for at least 5-6 days or placing in hot setting of clothes dryer for at least 30 minutes can also be effective. For specialty rugs consult a dry cleaner or carpet cleaning firm.
Once items are thoroughly cleaned they should be stored to exclude future infestations. Store in air tight rubber or plastic containers. Lids should fit tightly otherwise be sure to seal openings with tape. If items must be stored for long periods consider cold storage. Moth balls and flakes are effective. I know they stink but it's the vapors that do the work. Be sure to read label directions. Keep moth balls away from plastics and out of the reach of pets and children.
Usually sanitation and laundering can take care of beetle problems. If not, insecticides containing permethrin, bifenthrin, or esfenvalerate may be used along baseboards and in cracks and crevices. Be sure to read and follow all label directions. Cedar oil and mint oil may work as repellants. Cedar wood, however, loses the oils as it ages and cedar vapors must be contained to be effective. Click here for more information and pictures of carpet beetles.