Vaseline petroleum jelly formulations of selected insecticides: stirofos (2% A. I.); malathion (2%, 5% A. I.); crotoxyphos (5% A. I.) and methoxychlor (10% A. I.) were evaluated with a Vaseline standard for protection of horses against ear-feeding black flies. Two wipe-on formulations: stirofos (1% A. I.) and swish Starbar fly repellent were compared to a refined hydrocarbon standard. Vaseline, applied at the rate of 5gm per ear, afforded up to 3 days protection to the ears. The addition of selected insecticides did not enhance the protection of petroleum jelly. The oil formulations provided 2 days protection.