Tri-Tec 14 Fly Spray - 32 oz Protects against biting and nuisance flies, gnats, mosquitoes, deer ticks and lice. A triple-action insecticide containing natural pyrethrins and cypermethrin plus a sunscreen agent that helps prolong its effectiveness. Cypermethrin has double the killing power of permethrin and the pyrethrins provide repellency up to 14 days. This ready-to-use, water-based formula, is safe and gentle to horse's skin.