Carpet beetles, including the Varied, Black, and Furniture species, are small insects known for damaging materials containing natural fibers. The larval stage is the source of concern, consuming a wide range of organic matter. Understanding the natural life cycle of these insects, which often begins far from human dwellings, is the first step in managing their presence indoors.
Primary Habitat: The Outdoor Life of Carpet Beetles
Carpet beetles primarily exist as outdoor insects. Adult beetles spend their time feeding on the pollen and nectar of flowering plants, such as spiraea, crape myrtle, and wild asters, typically during the spring and summer months. This diet sustains the adult stage, which is focused on reproduction.
The larval stage requires a protein-rich diet to develop. Outdoors, female beetles seek out sources of animal protein to lay their eggs, such as abandoned bird, bee, or wasp nests, which contain dead insects, beeswax, and feathers. Larvae also feed on spiderwebs, animal carcasses, and other natural debris found in sheltered, undisturbed locations. The destructive larvae, often called “woolly bears,” consume these natural animal products.
Pathways Into Structures
The transition from the outdoor habitat to human structures is typically initiated by the adult beetle. Adult carpet beetles are strong fliers and are attracted to light, which often draws them toward windows and doors of buildings. They may fly in directly through open windows or doors, especially during late spring and early summer when they are most active outside.
Another common entry method is hitchhiking into the home on items that have been outdoors. Adult beetles can be accidentally brought inside on fresh-cut flowers, which often carry pollen.
They can also gain entry through small cracks, utility line openings, or vents, seeking shelter or a suitable environment for their offspring. Infestations may also begin when old bird or rodent nests attached to the eaves or inside chimneys are infested and the larvae migrate inside.
Indoor Attraction and Damage
Once inside, the adult female carpet beetle seeks out dark, undisturbed locations with an abundant food source for her larvae. The primary attraction for the larvae is keratin, a protein found in animal-based products. This includes materials like wool carpets, silk upholstery, leather goods, fur, and feathers found in down pillows or decorative items.
The larvae feed in secluded areas like closets, under furniture, or along baseboards. They may also consume non-keratin sources such as stored grains, dry pet food, and cereal products in pantries. Evidence of an infestation includes irregular holes or thinning patches on natural fiber items, which is distinct from the damage caused by clothes moths. As they grow, the larvae shed their bristly, brownish skins, leaving behind hollow casings and fine, powdery fecal pellets.