Because of the painful bites, general annoyance and potential for disease transmission, controlling these flies should have a high priority. These flies rarely enter barns and are most active at twilight. Using electric light insect traps in the barn may be useful for horseflies, but frequent use of repellents is the most practical control method. Blackflies, commonly called ear gnats, feed on blood inside the ear. They are found throughout the United States, especially near running water.
Female blackflies feed on blood every three to five days.
Extreme annoyance and itching result from the flies feeding inside ears, along the neck and chest, inside the thighs and along the underside of the horse. Repeated bites cause bloody crusts or scabs. Frequent use of repellents and ear nets also help control the attacks. Applying petroleum jelly inside the ears after clipping may help, too. Midges feed by inflicting painful bites which causes extreme itching, usually along the base of the tail, mane and withers.