"Tabanid flies are blood-suckers (the females) whose bites are extremely painful. They range from the small deer flies to the inch-long dive-bombing deer flies that strike fear in the hearts of both horse and human alike. These flies actually slice a chunk of flesh from the horse when they bite, and may bite multiple times." SCARY!
"A Hungarian study recently released showed that tabanids are primarily attracted by reflected polarized light from black and brown coats, a phenomenon called positive polarotaxis. They found the files to be much less attracted to white horses. White sheets may therefore help hide your dark horses from tabanids."