Flies cause significant welfare problems for horses through irritation, disease transmission, and the behavioral disruption of constant insect harassment. Effective fly control is a welfare priority.
Fly harassment during summer months causes continuous welfare stress that is easy for owners to underestimate because it is invisible as a chronic background condition. A horse that stamps, head-shakes, tail-swishes, and seeks shade constantly is expressing ongoing physical discomfort. For sweet itch-affected horses, the itching can be severe enough to cause self-inflicted wounds along the mane and tail. A comprehensive fly management approach — combining repellents, physical barriers, environmental management (muck removal, drainage), and housing during midge-active periods — addresses welfare much more effectively than any single measure.