Crawling insect killer! Made of amorphous diatomaceous silica, Diatomaceous Earth remains effective as long as it stays dry. Its killing action is mechanical rather than chemical. Insects die after losing body moisture through microscopic scratches caused by the Diatomaceous Earth. Apply with a duster like the Centro Garden Duster (ZTO937) for protection against most hard bodied insects. Can also be used as a non-toxic pet flea powder!