Carpet beetles are pests that feed off of things in your home that have some sort of animal origin. They could be found in anything from your trash can to a goose-down pillow. They originally acquired the name "carpet beetle" due to common infestations in woolen carpets. Carpet beetles will eat wool fabrics, but they will not infest synthetic fabrics that are commonly used in carpets today.
Infestations most commonly result from wild carpet beetle populations migrating to cooler areas in the heat of the summer. These cooler areas can be anything from a barn to a home. Infestations can start in areas as small as a pocket of household lint in a corner and move outward to the rest of your home.