Insects are more than annoying; they can also transmit serious diseases. You can't always be there to apply fly and insect protection, but Equi-Spot Spot-On Protection for Horses does the job for you. Applied once every two weeks, it provides long-lasting control against dangerous ticks that can spread Lyme disease and mosquitoes that may transmit West Nile Virus and Equine Encephalitis, as well as biting flies and gnats.