Carpet beetles belong to the Dermestidae family of beetles. Three types are the most common: the varied carpet beetle, the furniture carpet beetle, and the black carpet beetle. The term ‘dermestid’ is derived from Latin and Greek roots, “derma” meaning ‘skin’ and “esthiein”, meaning ‘to eat’. The aptly named dermestids feast on all kinds of animal tissue and animal-based products.
Varied carpet beetles are about 1/10 inch long, black, with an irregular pattern of brown, white, and dark yellow scales on their wing covers (elytra). Color can wear off the older beetles, making them look solid black or brown. These carpet beetles seek out bee, bird, and wasp nests and spider webs as the place to lay eggs.
The full-grown larvae are about the same length as the adults, but they are covered with thick tufts of hair that extend upright in plume-like fashion when they are disturbed. These larvae are narrower in the front and broader in the rear than other carpet beetle larvae, and they have alternating dark and light brown stripes running across their bodies. Adult varied carpet beetles often appear indoors in spring or early summer on windowsills.
Adult furniture carpet beetles appear slightly rounder and larger than adult varied carpet beetles. Their colors and markings vary greatly, but usually give a mottled appearance because of the white and gold-orange scales that are mixed with the black on their wing covers.
They may look black if these scales are completely worn and their undersides are white. The furniture carpet beetle larvae begin white then darken to chestnut brown or dark red as they age. They are narrower in the rear and broader in the front than the varied carpet beetle larvae, but they feed on the same foods.
The black carpet beetle adults range from 1/8 to 3/16 inch in length, and are glossy black and dark brown with brownish legs. Mature larvae can be up to 5/6 inch long. They can be colored from light brown to nearly black and are glossy, hard and with stiff, short hairs. Their bodies narrow toward the rear and end in a tuft of long hairs. In dry climates, the black carpet beetles tend to cause more damage to stored foods than to fabrics.
All carpet beetles pass through egg, larva, pupa, and adult stages. Depending on the type, an adult can lay from 40 – 90 eggs in a place that will provide food for the larvae after they develop from the eggs. About two weeks after the eggs hatch, the larvae begin feeding. The larval stage can range from 70 to 630 days, during which time the larvae carry on their destructive feeding. They prefer hidden, dark, undisturbed places.
When they are ready to pupate, they may burrow deeper into the food source or squiggle and burrow elsewhere. After they pupate, which takes about two weeks; they leave behind noticeable traces of their shed skins and fecal pellets, which are about the size of a grain of sand.
Carpet beetles have widely distributed household pests. It is their voracious larvae that cause extensive damage by chewing through clothing, furniture, bedding, carpets, book bindings, mounted animal specimens, game trophies, animal horns and bones, feathers, and decorations that contain fur, leather, wool, silk, or other animal products.
They do not feed on items made of synthetic fibers. Sometimes it is difficult to tell whether a clothes moth or a carpet beetle has caused damage. Generally, clothes moths will leave scattered holes, and carpet beetles will chew through a large area in one part of an article. Carpet beetle larvae will leave shell-like, brown, bristly textured thin skins when they molt.
Adult carpet beetles fly readily, especially during sunny, warm days, and they are attracted to light. In homes they are often found on the inside of windows and screens because they are trying to get outside to feed on one of their favorite foods, flower pollen. They especially seek out flowers like spiraea, crape myrtle, and buckwheat, which offer abundant pollen.
Cut flowers that are brought into the home should be checked for the presence of carpet beetle adults whose rounded bodies and short antennae resemble those of lady beetles. Depending on the type of carpet beetle, the adult females and males can live from 2 – 8 weeks.
Denying carpet beetles a food source is the best way to prevent them from becoming established in and around the home. Careful inspection will reveal possible infestation places for them. Wastes like old wasp skins, feathers, bits of old food, eggshells, hair, and animal droppings that are found in abandoned nests left by birds, wasps, hornets, and rodents in eaves, attics, wall spaces provide a prime food source for carpet beetles.
Such old animal ‘homes’, as well as spider webs, should be removed and destroyed. Whatever steps are possible should be taken to prevent areas from becoming future breeding and feeding sites for carpet beetles. When domestic animals hunt and bring home their prey, the remains from these expeditions should be quickly cleaned up and thrown away.
Thorough, frequent cleaning, especially with a vacuum cleaner, keeps hair, dead skin cell debris, and lint from accumulating. After vacuuming infested areas, the bag should be immediately sealed and discarded because it may contain live adults, eggs or larvae.
Rugs, carpets (particularly under furniture), draperies, upholstered furniture, closets and shelves where woolens and furs are stored, and pet use areas are favored carpet beetle territory. Cabinets storing dried foodstuffs that contain protein, including pet food, should be inspected regularly for signs of carpet beetles and any contaminated items should be disposed of immediately.
Food and perspiration stains on clothing can attract carpet beetles. Laundering in hot water or dry cleaning kills all stages of these pests. Before putting clothing that contains animal fiber in storage for long periods of time, these items should be laundered or dry cleaned, then stored in a pest-free, clean garment bag, chest, box or trunk that can be tightly sealed.
Mothballs, flakes and crystals can protect stored items from carpet beetles, but care should be taken in handling these pesticides because they can contain either paradichlorobenzene (PDB) or naphthalene. These chemicals should not touch bare skin or come in contact with food or cooking utensils. People and pets should not breathe these chemicals’ vapors in an enclosed space.
Mothballs and similar products can be placed between two pieces of paper or in envelopes that separate them from the layers of stored articles because they can melt plastic bags and damage plastic buttons and hangers. The containers in which mothballs are used must be tightly sealed because as the chemicals vaporize, the vapors must build up to a concentration that is strong enough to kill the carpet beetles.
Most closets are not airtight and are typically opened often, so they will not hold in the lethal vapors. Closets that are seldom used can be modified into suitable protective storage areas by sealing cracks around the door or by adding weather stripping to it.
Cedar oil in cedar chests is able to kill small carpet beetle larvae, but over time cedar loses its oil and thus loses its protective capability. Applying a new coat of cedar oil periodically will recharge the cedar wood’s effectiveness; however, the cedar chest must close tightly in order to provide maximum protection to its stored items.
Unfortunately, carpet beetles can infest the felts on piano hammers, resulting in damage that seriously affects the piano’s action and tone. A piano technician will need to attend to this problem and can possibly replace the animal based felts with ones made of synthetic fibers.
Scientists have discovered that some insects and other animals produce pheromones which are chemicals that attract animals of the same species. Sticky traps that are baited with carpet beetle pheromones are effective when placed in small, confined spaces for attracting and trapping adult males. Plain sticky traps can be used on window sills to catch adult carpet beetles that fly to windows.
Mounted specimens should be cleaned regularly to prevent infestation, and if a problem arises, they can be placed in a freezer below 18° F for at least 10 – 15 days, which will kill all stages of the carpet beetle.
Pesticides are a last resort to control carpet beetles. Children, the elderly and infirm, and pets can be especially vulnerable when exposed to chemical pesticides. Checking with a Poison Control Center about the risks of using any chemical pesticide in the home is wise before buying and applying such a product.
The chemicals in some pesticide formulations for carpet beetles may cause damage by staining or running on certain fabrics. Furniture, pillows, and mattresses that are stuffed with feathers or hair can be treated for carpet beetle infestation by a licensed pesticide applicator who can place the items in a fumigation vault. Lethal gas is injected, killing the carpet beetles in all their stages.
The pesticides used in these situations are dangerous and can be bought and used only by people licensed to handle them. This type of treatment is effective in killing the pests, but it does not prevent future infestations by them.