In the Winter of 2009 – 2010 my wife and I went to her family’s vacation home above Carnelian Bay, on the northwest side of Lake Tahoe, for a short weekend getaway.  Anticipating the cold weather, we took along some warm clothing.  Among the articles she took was an expensive cashmere sweater that she planned to wear if we went out to eat (as we usually do at least once during each trip to the lake).  When she unpacked the sweater she was horrified and saddened to discover that it had several holes where some sort of pest had been feeding.  At first I suspected clothes moths, but upon closer examination I realized that the damage was actually caused by Carpet Beetle Larvae.

Carpet Beetles are members of the Dermestid family.  There are three species of these insects infesting multifamily structures and single family homes in California, which can cause serious damage.  They are the Varied Carpet Beetle, Anthrenus verbasci, the Furniture Carpet Beetle, Anthrenus flavipes (LeConte) and the Black Carpet Beetle, Attagenus unicolor.

Adult Carpet Beetles feed exclusively on nectar and pollen from plants and can be introduced into the home by cut flowers and other plant materials.  They may also enter through open windows and doors.  Once inside they are free to mate and lay their eggs on larval food sources.  The larvae prefer secluded, dark places and cause all of their damage by feeding on their foods which include dead animals and animal products like leather, woolens, furs, textiles, pet hair, feathers, animal horns, whalebone and carpets made of natural fibers such as wool or silk.  They will also feed on dried plant products.  They do not feed on synthetics.  Diagnosing whether observed damage was caused by clothes moths or Carpet Beetles is not always possible.  However, Carpet Beetles tend to cause damage to a large portion of a garment or carpet, whereas clothes moths more often create scattered, smaller holes.  The larvae also tend to leave hairy looking cast skins during molting.  These skins and the absence of webbing are good indicators that Carpet Beetles are present.  When they are ready to pupate they will move deeper into the food source or move to another, even more secluded location such as between carpeting and base board moldings.  Unlike clothes moths, Carpet Beetle larvae do not spin webs but their presence can be detected by their droppings, which are about the size of a grain of salt.

Depending on the species, Carpet Beetle females will lay from 40 to 90 eggs each.  The eggs will hatch anytime from 6 to 20 days and reach maturity in from 70 to 630 days.  Pupation lasts from 8 to 17 days.  The adults live from 2 to 8 weeks.

Control is difficult to achieve because of the beetles’ instinctive tendency to find food in secluded, obscure places.  They may be spread out in various locations within a building.  Elimination of food sources is critical when dealing with these pests.  It is essential that accumulations of pet hair, dead insects and other organic food sources be cleaned up, sealed in plastic bags and discarded in the trash outdoors.  Throw out badly infested items.  Check cut flowers for Carpet Beetles prior to bringing them indoors.

Food and perspiration stains are attractive to these pests.  Fabrics can be protected by dry cleaning or a thorough laundering in hot water.  This will kill all four stages of these insects.  Regular, thorough cleaning of rugs, fabric window coverings, upholstered furniture and closets and other places likely to contain the beetles is effective in controlling them.  Regular vacuuming of infested areas is also helpful.  Be sure to immediately dispose of the vacuum bag, outdoors so that it does not become a source of re-infestation.

Inspect stored items and hang them in the light annually to check for infestations.  If Carpet Beetles are discovered dry clean or wash these items to destroy the insects and seal them in protective plastic bags or other protective containers before storing or usng them again.  Using resin strips, moth balls or moth crystals are good for repelling the adults but will be ineffective against the larvae unless they and the items being stored are in tightly sealed containers where sufficient fumes may build up to kill the insects.  Since these products contain oils, care should be taken to avoid direct contact with the stored items.  Some plastic buttons may actually soften and melt into the fabric of the garment, if they are in direct contact with these chemicals.  Larger items such as mattresses, upholstered furniture, items containing natural stuffing or feathers and special items that cannot be cleaned, like stuffed animals, if infested, should be treated in a sealed fumigant container, by a trained technician.  Simply spraying the surfaces of these items will not control the beetles.

Prevention and cleaning are the best ways to control Carpet Beetles however there are areas where insecticides must be used.  These are useful with articles which cannot be cleaned dry cleaned, laundered or treated in a fumigation container.  If doing it yourself buy a product that specifically lists Carpet Beetles and apply it, according to label directions, as spot treatments.  Try to limit sprays to the edges of floor coverings, under rugs and furniture, floors and closet walls.  Also treat shelves where susceptible items are stored, cracks, crevices and lint accumulating areas.  DO NOT spray clothing or bedding.  Follow reasonable practices to check these items for color fastness prior to actual treatment.

 Varied Carpet Beetle photos by: André Karwath aka.  creative Commons Attribution ShareAlike 2.5license