Diatomaceous earth is a fine powder composed of sharp silica particles that can be used to control fleas. When insects such as fleas come in contact with the powder, it slices holes into the insects that cause them to dry out and die, according to About.com.
Diatomaceous earth can be sprinkled on pet bedding and carpets, and it can be placed in the yard to help control fleas and other insects. It only works when it is dry. It is non-toxic but can be irritating to the skin and respiratory tract. Diatomaceous earth is made out of the fossilized remains of diatoms, a type of algae.