Mosquito Halt Repellent Fly Spray for Horses provides quick knockdown, kill and repellency for control of mosquitoes that may transmit West Nile Virus and other deadly mosquito-borne diseases. Also provides immediate and residual control of face flies, stable flies and house flies. Mosquito Halt contains 0.20% permethrin, 0.13% prallethrin and 0.50% piperonyl butoxide, plus soothing aloe, lanolin and PABA sunscreen.