Hartz® InControl™ Flea & Tick Drops for Cats contain an effective insecticide which kills adult fleas, ticks and mosquitoes and an insect growth regulator which prevents flea eggs and larvae from maturing into adults. Afer application, through its natural movement, your pet's skin and hair oils carry the flea and tick drops over the pet's body for protection up to 30 days. For cats and kittens over 12 weeks old. Contains 4 monthly treatments.