Beetles spend their entire life searching for a mate and reproducing. Supermarket pesticides will kill adult beetles, however it will not affect the larvae. These beetles can be hard to get rid of alone, as larvae often hide inside wood and in tight crevices.
Carpet beetles feed on pollen as adults, however, their larvae will eat right through furniture, clothing, carpets, and other natural fibers. They will also eat animal products including leather, hair, feathers, wool, silk, dead insects, dried meat, and dried plant material.
Adult females will often lay their eggs in undisturbed, dark areas such as under baseboards, in closets, under furniture, in air ducts, and more. Once larvae hatch, they feed on any organic materials they can get to, and will cause extensive damage if not controlled. This can be problematic in kitchen cupboards and pantries if you do not regularly change out your groceries.
The best way you can prevent and control beetle infestations is by vacuum cleaning on a regular basis, dry cleaning and airing rugs and other fabrics outside, and removing old bird and insect nests. Naphthalene balls are a very effective deterrent, and scent and pheromone traps may help to control adult beetles.