It is made up of fossilized diatoms, a type of single-celled planktonic algae that lived in the oceans and freshwater lakes of old. The silica rich shells of these microscopic organisms give this chalk-like substance exceptional porosity and an abrasive property.
Diatomaceous earth is a non-toxic way to control pests in the garden. It is effective against all insect pests that crawl on plants because contact with the powder is extremely dehydrating., also for the slugs!