Prozap War Paint Stick Fly RepellentApply War Paint in very small amounts only where flies congregate. When applied to the horse, it attaches to the hair and slowly releases the insecticide over a period of weeks. Full body fly control does not usually occur on the horse until 1 2 days after the application. It is not only an insecticide but a repellent as well. After 2 3 weeks War Paint will become powdery and fall off the horses hair with no adverse effects at all.