Carpet beetles are insects are pests in warehouses, homes, museums, and other locations where suitable food exists. In California, three species of carpet beetles cause serious damage to fabrics, carpets, furs, stored foods, and preserved specimens.
VARIED CARPET BEETLE
The varied carpet beetle is common in California. Outdoors, female beetles search out spider webs and nests of bees, wasps, and birds in which to lay their eggs. The nests contain dead insects, beeswax, pollen, feathers, or other debris that can serve as larval food. Indoors, beetles deposit eggs on or near wool carpets and rugs, woolen goods, animal skins, furs, stuffed animals, leather book bindings, feathers, animal horns, whalebone, hair, silk, dried plant products, and other materials that can serve as larval food.
Mature larvae are about the same length as adults and are covered with dense tufts of hair that they extend upright to form a round plume if disturbed. They have alternating light and dark brown transverse stripes and are distinguishable from other carpet beetle larvae because they are broader in the rear and narrower in front. Adults usually appear in spring or early summer; indoors, they are often seen near windows.
Carpet beetle adults do not feed on fabrics but seek out pollen and nectar. They are attracted to sunlight and are commonly found feeding outside on the flowers. that produce abundant pollen. Be careful not to bring these pests into the home on cut flowers—with their rounded bodies and short antennae, carpet beetles somewhat resemble lady beetles in shape. Damage is caused by the larval stage of beetles. Larvae feed in dark, undisturbed locations on a variety of dead animals and animal products, such as wool, silk, leather, fur, hair brushes with natural bristles, pet hair, and feathers; They do not feed on synthetic fibers.
Several species of beetles commonly attack a wide variety of foods: the warehouse beetle, the sawtoothed grain beetle, the merchant grain beetle, the confused flour beetle, the red flour beetle,and the drugstore beetle and the cigarette beetle. Other beetles that feed primarily on seeds or whole grains include the lesser grain borer, the bean weevil, the granary weevil, and the rice weevil.
SAWTOOTHED GRAIN BEETLE AND MERCHANT GRAIN BEETLE
The sawtoothed grain beetle and the merchant grain beetle are slender, flat, brown beetles. Both beetles have six sawlike tooth projections on each side of the thorax. In both larval and adult stages, these beetles feed on all food of plant origin, especially grain and grain products like flours, meals, breakfast foods, stock and poultry feeds, coconut, nutmeats, candies, and dried fruit; it is not uncommon to find these beetles infesting pet food, bird seed, and rodent bait.
The confused flour beetle and the red flour beetle are very similar in appearance. These beetles have a very wide food range including cereals, damaged grains, grain products, shelled nuts, dried fruit, chocolate, drugs, and herbarium and museum specimens.
The warehouse beetle feeds on a wide variety of foods including cereals, candy, cocoa, cookies, cornmeal, fish meal, pet foods, flour, nuts, dried peas and beans, pastas, potato chips, spices, dead animals, and dead insects. The setae of this beetle are shed within the infested food product and can be irritating to the mouth, esophagus, and digestive tract if they are ingested; consequently any food found infested with this beetle should be discarded.
CIGARETTE BEETLE AND DRUGSTORE BEETLE
The cigarette beetle and the drugstore beetle closely resemble one another, but the cigarette beetle is more common. The cigarette beetle feeds on cured tobacco, cigarettes, and cigars. It also feeds on dried herbs, spices, nuts, cereals and cereal products, dried fruit, seeds, and animal products such as dried fish and meats, hair, and wool. In the home this beetle is most commonly found in pet foods, cereals, nuts, and candy. It may also infest dried pepper arrangements, wreaths, and spices such as chili powder or paprika.
The drugstore beetle is a very general feeder, attacking a great variety of stored foods, seeds, pet foods, spices, and pastry mixes, and has been said to “eat anything except cast iron.” It gets its name from its habit of feeding on almost all drugs found in pharmacies. In the home, however, the most common food materials infested by this beetle are pet foods, drugs, and cereals.
Pantry pests damage food by contaminating it with their bodies and their by-products. The larval stage of the Indianmeal moth produces frass and webbing, and some beetle larvae produce secretions that give food a disagreeable odor and taste. Setae (hairs) from the warehouse beetle can irritate the mouth, throat, and stomach of people who eat infested products. In addition, pantry pests might introduce microbes into the food that could produce mycotoxins (highly carcinogenic compounds), especially if the food is stored in warm, humid conditions.