Symptoms of dermestid beetle infestations include the discovery of damaged articles, the appearance of larvae migrating in the vicinity of infested materials or the appearance of adult beetles around sources of light such as in window sills. Larval food sources are many and often difficult to locate, but are usually in dark, undisturbed locations. Larvae are brown and hairy, usually with longer tufts of hair (setae) on the back end. Size and shape depends on species, but they are usually less than ½ inch long. Adults are somewhat characteristic in size and color patterns: The larder beetle, Dermestes lardarius (Linnaeus), is 5/16 inch long, dark brown, with each wing cover (elytra) marked with a wide, yellow band and three black spots. The body is covered with fine yellow hairs. The black larder beetle, D. ater DeGeer, is similar but black and lacking the dull yellow band on the wing covers. The hide beetle, D. maculatus DeGeer, has elytra that are uniformly dark with the under surface is white and the ends pointed sharply. The black carpet beetle, Attagenus megatoma (Fabricius), is less than 3/16 inch long and black to dark brown. The varied carpet beetle, Anthrenus verbasci (Linnaeus), is less than 1/8 inch long and has a color pattern of white, brownish and yellowish scales on the back. The furniture carpet beetle, A. flavipes LeConte, is similar to the varied carpet beetle, but the elytra terminate in a cleft.
There are a number of other species of dermestid beetles. One of the worst stored-product pests in the world is the khapra beetle, Trogoderma granarium Everts. It prefers stored dried vegetable products (grains, seeds, flour, cereal, hay, straw) but will also attack animal products. Originally from India, it was introduced into the western United States during the 1940's and has been under federal quarantine. It is periodically detected in grain shipments entering U.S. ports.
Life Cycle: Adults overwinter in cracks and crevices, entering buildings in spring and early summer seeking food sources. The female of the larder beetle lays eggs which hatch in 12 days or less. Larvae develop through 5 to 6 stages (instars) before pupating. Cast skins from larval development often accumulate around the food source. Carpet beetles pupate in their last larval skin and may remain there for several weeks. The black larder beetle develops from egg to adult in about 6 weeks, while the varied carpet beetle can take almost a year to develop (egg - 17 to 18 days; larvae - 222 to 323 days through as many as 16 instars; pupae - 10 to 13 days).
Habitat, Food Source(s), Damage: Mouthparts are for chewing. Adult carpet beetles feed on pollen and nectar in the spring. Larvae of the larder beetle, the black larder beetle and the hide beetle feed on animal products, including meats, cheeses, animal skins, feathers and horns. Black and varied carpet beetle larvae feed on fabrics containing wool and other animal hair in clothing, furniture and other household materials. Larvae are capable of digesting keratin, the protein in animal hair and feathers. They may also damage materials of plant origin (cotton, linen, silk) and synthetic materials containing nutritious contaminants. The varied carpet beetle is often found in collections of dead, dried insects and other arthropods kept in unprotected, loosely-fitting, dark storage boxes. Adult carpet beetles can be found in the spring on flowers. Adults often accumulate on window sills in infested buildings.
References and Resources: For additional information, contact your local Texas or other Extension agent; Drake 1920; Slater and Baranowski 1978; http://insects.tamu.edu.