Get tough on adult fleas, ticks, flea eggs and larvae. FRONTLINE Plus has 2 tough killing ingredients. The 1st, fipronil, kills adult fleas and ticks. The 2nd, (S)-methoprene, attacks flea eggs and larvae. They work together to kill all month long. Plus, it breaks the flea life cycle. By also destroying the next generation of flea eggs and larvae, FRONTLINE Plus gives you the power to help prevent a flea infestation on your pet. Ask your vet about the flea and tick protection of FRONTLINE Plus.