What is diatomaceous earth?

Diatomaceous earth (DE) is a geologic deposit of fine, grayish material composed chiefly or wholly of the remains of diatoms; it may occur as a powder or as a porous, rigid material; used in insecticides. To insects DE is a lethal dust with microscopic razor sharp edges. These sharp edges cut through the insect’s protective covering drying it out and killing them when they are either dusted with DE or if it applied as a wettable powder spray. If they ingest the DE it will shred their insides.