Horn flies cause significant welfare harm through blood-feeding stress in cattle, and integrated pest management approaches provide effective control while minimizing chemical resistance development.
Horn fly welfare harm is often underappreciated because it occurs gradually and cattle adapt behaviorally to fly loads. However, the energetic cost of fly irritation behavior, blood loss from heavy infestations, and the psychological stress of continuous irritation represent real welfare harm. Above threshold fly loads cause cattle to bunch and restrict feeding behavior -- direct welfare and production impacts. Integrated pest management that maintains fly loads below welfare-impacting thresholds using rotating control methods preserves treatment effectiveness longer than reliance on single chemical classes.