Sweet itch is an allergy which most horses have to the bites of tiny midgets. The itching sensation of their bites makes horses rub themselves raw on anything they can find to get rid of the irritation. Normally, the mane and tail of the horse gets most affected. The midgets usually bite around dawn and dusk, so it would be best for you to stable your horse at these times. Also, if your horse suffers from sweet itch, you can get benzyl benzoate from your chemist. When this is rubbed onto the area that is being irritated, it helps to relieve the itching.