The nice thing about DE (the food grade) is that it's perfectly safe for consumption by any critters, including us! It's not a poison; it kills physically rather than chemically. At the microscopic level, the grains are very, very sharp...like shards of glass. When bugs with a hard shell get it on them, it works its way into the joint areas and as they move it cuts tiny openings in their shell and as the moisture in them leaks out, they shrivel up and die. On other critters, it's totally harmless, but those little bugs who need that hard carapace, it's deadly. I regularly dust my coop and bedding to keep any pests down.