FRONTLINE Plus is the longest-lasting, most complete spot-on flea and tick protection available. Research indicates that FRONTLINE Plus not only kills 98-100% of adult fleas on your dog within 24 hours, it also contains a special ingredient that kills flea eggs and larvae, too, and keeps ALL stages of fleas from developing. FRONTLINE Plus completely breaks the flea life cycle by effectively stopping the development of new fleas. And, FRONTLINE Plus kills all stages of 4 major ticks including the ones that may transmit Lyme disease and Rocky Mountain spotted fever.