FRONTLINE® Plus for Dogs and cats spreads from the single point of application, rapidly covering the entire dog or cat and localizing in the hair, on the surface of the skin and in the sebaceous glands. These glands act as a reservoir, continuously replenishing FRONTLINE Plus for Dogs onto the skin and hair coat, so it keeps working even if the dog or cat gets wet.Even if you have treated your pet for fleas, some fleas may lay eggs before dying, therefore it is important to tackle flea eggs. FRONTLINE Plus for Dogs and cats kills fleas before most have time to lay eggs. The (S)-methoprene in FRONTLINE Plus for Dogs and cats prevents development of flea eggs and flea larvae, breaking the flea life cycleYour dog or cat needs to be dry at the time FRONTLINE Plus for Dogs and cats is applied and remain dry 24 hours after application.