The appearance of carpet beetles varies depending on their stage in life; young larvae resemble millipedes, while adults have dark brown to black shells and have distinct oval shapes. Beetles grow quickly, and as such, move rapidly through different stages of appearance. They shed their shells and skin as they grow, and they change shapes and colors frequently.
Larvae appear like millipedes from birth through the end of the larvae phase. These juveniles have long, round bodies and are red-tinted or light brown in color. Some species have short hairs, and others have distinct tufts of fur growing from their backsides. Adults are dark-brown to black in color, and they have hard outer shells. Some have colored scales with different patterns, and they all have long antennae.