Horse flies tend to attack animals more than humans. The females lay eggs on vegetation near water, and the larvae develop in moist soil near streams, marshes, and ponds. Emerging adults are fast, strong fliers. Keeping doors and window screens in good repair can help keep horse flies out of the house. Wearing long sleeve shirts, long pants, and netting for face protection can reduce bites from horse flies when outdoors. Spraying outdoor areas with an insecticide labeled for this use can help reduce horse fly infestations.