SHIELD aids in the control of synthetic Pyrethroid susceptible nuisance flies and biting insects and an aid in the control of Queensland itch on horses. As a unique ?pour-on? for horses, SHIELD not only repels flies, it lasts longer than sprays and is also easier to apply. Simply pour it along the backline as per the directions. SHIELD controls the following biting insects: Domestic & Bush Flies, Stable Fly, Biting Midges, Buffalo Fly, Mosquitoes.