Flea free is an all-Natural liquid supplement, which when added to the pet’s drinking water, is ingested, and goes to work internally. When Flea Free enters the pet’s system, it produces an enzyme which shields the protein the female needs to lay eggs, not able to find what she is looking for she exits the animal in search of another host to feed on. If she does not draw blood every 20 to 24 hours she will die. The male doesn’t bite and having nothing to fertilize leaves the animal also. This breaks the reproductive cycle, works on all blood feeding insects, fleas, ticks, mites, lice, mosquitoes, and biting flies.