Diatomaceous earth, Caltron’s Diatom Powder food grade is not poisonous; it does not have to be eaten in order to be effective. Diatomaceous earth (DE POWDER) causes insects to dry out and die by absorbing the oils and fats from the cuticle of the insect's exoskeleton. Its sharp edges are abrasive, speeding up the process. It remains effective as long as it is kept dry and undisturbed.