Diatomaceous Earth is a 100% natural product, prepared from the fossilised remains of ancient shell creatures, so is totally inert and safe to humans and animals. It is used on animals to protect against external parasites (lice, fleas, mites), internal parasites (worms), and for general good health. It can be added to your chickens feed at roughly 2-5%. When applying directly to your hens, apply liberally using a puffer bottle but make sure to coat under the wings and in their nest box.