They are frequently found outdoors in flowers and are most numerous in the spring and early summer. They lay eggs either indoors or outdoors, beginning 4 to 8 days after the adult emerges. Each female lays approximately 50 eggs over a period of about 3 weeks, after which she dies. Indoors, these eggs are deposited in accumulations of lint, in air ducts, underneath baseboards and other similar places. Eggs hatch in 6 to 11 days in warm weather.
Body color varies from a light brown to almost black.
They can develop under a wide range of temperature and humidity conditions, and are much less susceptible to environmental changes than are clothes moths. They tend to avoid lighted areas, so are found most frequently in the lower parts of clothes closets, rolled up or wrapped into woolen materials, at the edge of carpeting under baseboards, or inside upholstered furniture. Mature larvae can wander rather widely, so may be found anywhere in a building. It is not at all unusual to find them in a bathtub, kitchen sink, or even crawling on walls and ceilings. Black carpet beetle larvae are general feeders, feeding on dead animal materials, hair, fur, hides and horns, as well as the usual woolen products and many plant materials such as cereals, stored grain or nuts.