New Year visits by tiny beetles: Carpet beetles and their kin, Dermestidae
But a few millimeters in length, tiny, handsome carpet beetles sometimes appear in my home on wintry days.
As we say good riddance to 2020, and welcome in a hopeful 2021, Bug of the Week will spend some time catching up with a few fascinating, fearsome, and funny creatures found in and around our homes. This week we visit tiny recyclers of organic matter called carpet beetles that can sometimes become pests. On a warmish winter day, I occasionally spot a rather lovely small beetle scaling a wall or scooting across a countertop in my home. Carpet beetles get their name from their proclivity to breed in a wide variety of natural substrates containing the protein keratin, which is found in felt, silk, feathers, pet hair, animal hides and carcasses, and, yes, woolen carpets. They become pests when colonizing a drawer, closet, or box where sweaters or other garments are stored. Adult beetles deposit eggs that hatch into hungry, tiny larvae which nibble away fibers, creating holes or sinuous trails in fabrics.
Hairs on dermestid larvae can cause dermatitis to some people.
The larvae are very hairy little beasts, covered with long hairs or setae. Prolonged exposure to these hairs festooning the bodies of carpet beetle larvae has caused dermatitis in some people. Carpet beetles belong to a larger clan of recyclers called dermestids, or hide beetles. Hide beetles provide an important service to museum curators by virtue of their ability to strip skeletons of virtually all muscle and sinew, producing lovely bare bones. However, dermestids create problems for professional and amateur entomologists when they invade collections of pinned and preserved specimens. Larvae bore into dead insects and consume proteinaceous tissue within. As they feed, small pellets of waste products called frass litter the area beneath the infested specimen. This is the classic hallmark of a dermestid attack.
During winter, pretty carpet beetle adults and their very hairy larvae sometimes wander about my desk, table, and walls. In the wild, other dermestids are some of the last visitors to animal carcasses. Larvae like this one can remove skin, muscle, and other connective tissue, leaving behind nothing but bone.
Uh oh, ragged holes in my woolen cap look like the handiwork of carpet beetles.
Thwarting carpet beetle infestations is relatively straightforward. Before storing any garment made of natural fibers be sure it is laundered or dry cleaned and stored in a sealable bin or bag. If these rascals have already established a foothold somewhere in your home, try to ferret out their location. This could be a seldom used woolen rug in the basement, a box of sweaters in the attic, or a blanket, dress, or sport coat in a closet. Carpet beetles can also breed in carcasses of dead insects so maybe a pile of dead stink bugs in the attic is the source of an infestation. Some species of dermestids breed in stored products like grains, pet food, nuts, and spices. We met a caterpillar with similar habits, the Indian meal moth larva, in a recent episode. Once you locate the infestation, discard or destroy the material serving as the source of the infestation. In the case of carpets and rugs, vacuuming and deep cleaning will help. A lightly infested blanket or scarf can be salvaged by either placing the item in a deep freezer that is below 0 degrees Fahrenheit for several days, or by heating it above 130 degrees Fahrenheit for several hours. Temperature extremes can kill eggs, larvae, pupae, and adult carpet beetles. But please don’t set the item on fire or burn your house down.
An untidy pile of frass behind a dead insect specimen is a sure indication of a dermestid beetle infestation.
How does a person who should know better wind up with carpet beetles in a home? The answer lies in the back of a closet where show-and-tell bugs used in STEM outreach are stored. In a tray of preserved scarab beetles, one unfortunate specimen bears an untidy deposit of frass attending its rear-end. Since dead beetles don’t engage in post-mortem voiding of waste, the pile of frass is the tell-tale signature of carpet beetle larvae dining inside the dead scarab. Bad luck for the scarab translates to good luck for sharing a tale of carpet beetles.
Bug of the Week wishes everyone a happy and healthy New Year free of all plagues!
Acknowledgements
Information in this episode originated in great articles written by Whitney Cranshaw at Colorado State University and Michael Potter at the University of Kentucky. Learn more about these creatures at the following websites:
https://extension.colostate.edu/topic-areas/insects/carpet-beetles-5-549/
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