Frontline Plus is a monthly topical flea and tick preventative for dogs and cats. Frontline Plus kills 100% of adult fleas on your pet within 12 hours and 100% of all ticks and chewing lice within 48 hours. Frontline Plus contains an insect growth regulator, S-methoprene, which kills flea eggs and larvae. It's effective against all stages of the brown dog tick, the American dog tick, the lone star tick and the deer tick (the major carrier of Lyme disease).