The American Horse Fly is one of the largest flies in North America, with iridescent green eyes and a robust dark body. Only females blood-feed, using scissor-like mouthparts to slash through skin — causing painful, slow-bleeding wounds. They are persistent biters around horses, cattle, and humans near water. Males feed solely on nectar.
Best time to see a American Horse Fly
The best time to see a American Horse Fly is June–July, when about 62% of U.S. sightings happen, based on 575 research-grade iNaturalist observations.
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