Show spray for flies according to J J davis entomologist 0 at purdue university a good homemade spray for keeping flies off cows can be prepared by mixing one pint of oil of tar far with one gallon of used crank case oil another recommended spray may be made by mixing one gallon of fish oil two ounces of oil of tar two ounces of oil of pennyroyal and one half pint of kerosene the most satisfactory way to apply these Is with a small compressed air sprayer that can be obtained at most stores handling spray materials there are several other reliable commercial fly sprays on the market |