Diatomaceous Earth is the fossilized remains of microscopic shells created by one celled plants called diatoms. These plants are found in all bodies of water and serve as basic food for aquatic life, just as grass is the basic food for land animals. These one celled fresh water plants have a tubular surface with holes on the walls that make it an abrasive substance which is deadly to insects such as bed bugs, fleas, ticks and other insects. Diatomaceous Earth kills insects by physical action, not chemical, it will lacerate the insect and dehydrate it until it is killed. The fresh water diatoms form a much harder shell that is less fragile than those found in salt water making it more effective.
Perma-guard's Fossil Shell Flour Diatomaceous Earth is typically used as an anti-caking agent in animal feed because it also keeps insects out of the animal feed. DE will also help as a regular dietary supplement for livestock or pets because it helps to control parasites and worms.
Because of the abrasive nature of Diatomaceous Earth to insects it has more commonly been used to control outbreaks of bedbugs and fleas. The reason this is so effective is because unlike other insect repellents which go inert after a short while, DE will continue to be effective long after it has been applied. Within a short time Diatomaceous Earth can kill a large infestation of unwanted insects within the home.
Although Food Grade Codex Diatomaceous earth (Fossil Shell Flour) was not meant to be used as an insecticide it is just as effective. The DE meant to be used as an insecticide simply adds extra chemicals to excite the insect so the Diatomaceous Earth works more quickly, but these extra chemicals cause the DE to be less environmentally friendly and more hazardous to your health.