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 18 hours and 100% of all ticks 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). Frontline Plus remains waterproof for 30 days.