Although named for equines, horseflies bite and feed off the blood of various types of livestock. These sharp, painful bites cause misery to their victims, and can potentially spread disease. It's only the female of the species that drinks blood -- the males consume plant nectar.
Female horseflies usually lay eggs near water sources. In the larval stage, horseflies eat tiny organisms found in water or on land, along with decaying materials. Horseflies can remain in the larval stage for up to three years.
Female horseflies land on cattle, horses, goats and sheep. They land on their prey and slash an opening with their blade-like mouth, drinking the resulting blood. Livestock constantly bitten by horseflies can suffer significant blood loss and possible anemia. Because bitten animals react so strongly, a single horsefly might move from one animal to another in a herd to get her blood meal. Regular use of fly repellents offers livestock some protection from these creatures.
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