Flies and other biting insects cause significant and often underestimated welfare harm to horses through constant irritation, stress, wound contamination, and disease transmission.
The welfare impact of biting insects on horses is substantial and year-round in warm climates. Constant harassment prevents normal rest and feeding, causes chronic stress, and leads to self-injury through rubbing and stamping. Sweet itch in susceptible horses causes extreme distress with severe skin damage. Effective fly control is a core welfare obligation for horse owners.