The Science of De Flea - The active ingredients in De Flea products work together to soften the waxy exoskeleton of fleas, ticks, lice, mites and other insects. Once the insect's armor has been penetrated, its internal organs are saturated and the insect quickly bursts. De Flea products work for all stages of an insect's life cycle: eggs, larvae, pupae and adult - effectively eliminating all insects from the home.