For SPISH: DE is short for "diatomaceous earth" which is a fossilized type of algae that is a natural insecticide as well as a natural abrasive, often used in cat litter and water filtration as well as a product in blood clotting studies and dynamite. Used in chickens and other animals as a flea & lice treatment as it causes the protective coating on fleas, roaches, etc. to rub off and causes them to dehydrate.