Frontline Plus provides your dog with the most complete spot-on flea and tick protection available. In addition to killing 98-100% of adult fleas on your dog within 24 hours, Frontline Plus contains a special ingredient that kills flea eggs and larvae, too, and keeps all stages of fleas from developing. By effectively stopping the development of new fleas, Frontline Plus completely breaks the flea life cycle. And, Frontline Plus kills all stages of 4 major ticks including those that may transmit Lyme Disease and Rocky Mountain Spotted Fever. It's completely waterproof. To Ensure Proper Flea And Tick Control And Minimize Risk Of Infestation The Manufacturer Recommends Continuous Year-round Treatment; Even In Winter Months.