Carpet Beetles

by Nick Gromicko, CMI®

Carpet beetles are household pests capable of destroying various household items. Inspection and knowledge of their habits can prevent costly destruction.

Life Cycle and HabitsFurniture carpet beetle, adult and larvae

Female carpet beetles will lay 50 to 100 small, pearly-white eggs on protected surfaces near a food source, such as the lint around baseboards, in the ductwork of hot-air furnace systems, and on wool clothing in storage. Larvae emerge once the eggs hatch after six to 11 days in warm weather, although they may require more time in cool weather. The larval life spans between 250 to 650 days, most of it spent scavenging for protein-rich food in dimly lit areas. By the time they reach adulthood, carpet beetles will live for only another few weeks or months, and they will no longer damage household goods. Unlike larvae, adults are attracted to light and can be found busily flying around windows or feeding on pollen outdoors.

Types of Carpet Beetles
Carpet beetles come in several types of subspecies, including the following:
  • black carpet beetle:  Adults are oval and shiny black, with brownish legs. They vary in length from 1/8-inch to 3/16-inch. Larvae are golden to dark brown, and about 1/2-inch long. The body is narrow and elongated, and narrows toward the rear.
  • varied carpet beetle:  Adults are 1/10-inch to 1/8-inch long and nearly round. The top surface is usually gray, with a mixture of white, brown and yellow scales, and irregular black crossbands. The bottom surface has long, gray-yellow scales. Larvae are about 1/4-inch long, and light to dark brown in color. The body is wide and broader at the rear than the front.
  • furniture carpet beetle:  Adults are 1/16-inch to 1/8-inch long, nearly round and whitish, checkered with black spots, each outlined with yellowish-orange scales. The bottom surface is white and the legs have yellow scales. Larvae are about 1/4-inch long, elongated and oval, and thickly covered with brownish hair.
  • common carpet beetle:  Adults are 1/10-inch to 1/8-inch long, nearly round, and gray to black. They have minute, whitish scales and a band of orange-red scales down the middle of the back and around the eyes. Larvae are similar to those of the varied and furniture carpet beetles.

Damage and Inspection

Carpet beetle larvae prefer to feed in dark, protected places, consuming and damaging wool, fur, silk, cashmere, feathers, bone, and synthetic and cellulose-based fibers that contain some amount of animal fibers. Check for larvae and their cast skins under baseboards, and in and under upholstered furniture, air ducts, stuffed animals, stored cereals and grain, abandoned bird and wasp nests under eaves, and in attics, and clothes closets. Stored items are vulnerable to severe damage, so Fabric holes typical of carpet beetle infestationperiodically inspect woolens and other susceptible items. Also, inspect for improperly sealed windows, as these are a likely entry point for carpet beetles, although the insects are small enough that it may be impossible to completely prevent their entry.

It is important for the homeowner to know the difference between carpet beetle damage and damage caused by other pests, such as clothes moths. Fortunately, the distinction is simple; moth infestations are often accompanied by adult moths flying nearby, and you will likely find adult moths, pupae casings or cocoons and larvae in your clothes. Carpet beetles are less conspicuous, as they typically move elsewhere after feeding, and the adults spend much of their time outdoors.  Telltale signs of beetle-damaged clothing include small, irregular holes, especially around the collar.

Chemical Treatments  
Homeowners interested in pest control measures for eliminating carpet beetles indoors have the following options:
  • permethrin:  This product is relatively safe and is recommended for mild infestations.
  • cyfluthrin:  This poison is longer-lasting than permethrin.
  • pheromone traps:  These baits attract adults using special scents, which lures them into glue from which they cannot escape. This measure will diminish the number of active adults, which, in turn, will reduce the risk of future infestations elsewhere in the building.
  • diatomaceous earth and silica aerogel:  These substances, known as desiccants, cause insects to lose moisture and, in small quantities, they are relatively harmless to humans.

Non-Chemical Treatment

  • Sanitation is the best way to avoid carpet beetle infestations. Practice thorough and frequent vacuuming and sweeping of carpets, rugs, draperies, closets, drawers, upholstery, air ducts, corners, baseboards, and other places where lint and hair accumulate.
  • Wash your clothes to remove adults, larvae, eggs or pupae. Be sure to throw away badly infested pieces.
  • Remove dead insects and rodents. Carpet beetles feed on animal waste, including their excreta and carcasses, so be sure to inspect for dead insects, especially around windowsills, and control any rodent population in your home. Avoid poison baits, as dying mice may be found more quickly by the beetles than by you.
  • Thoroughly inspect second-hand items before bringing them into your house and immediately launder them, as carpet beetles often hitchhike into homes on clothing, rugs, quilts, and other items of animal origin.  
  • Tightly seal windows and other openings, especially near flowers and shrubbery, where adults are likely to be found. 
In summary, carpet beetles are a common source of damaged household items, and measures should be taken to prevent infestation.