Name: Musca autumnalis
Alias: Face fly. This insect looks almost the same as the average house fly, with a few distinctions. The face fly is slightly bigger than its cousin and has more pronounced grey stripes across its back. The biggest distinction is their character. Face flies prefer to spend the majority of their time around the face; specifically, the eyes, ears, mouth and nose of livestock. They feed on the secretions that are high in protein. Females lay their eggs on fresh cow manure, spending their entire juvenile life in the cow patty until they emerge as adults. They rest at night away from their food source.
Crimes: Their most common crime is the annoyance. They annoy everyone and everything they come close to. It is no wonder that cattle have a built in fly swatter, or that horses learned to stand head to tail during the summer months to help each other with fly control. They are very persistent and won’t stop harassing until they are dead. In some cases they can transfer diseases, such as eyeworm and pinkeye.
Redeeming qualities: Face fly maggots contribute to the natural breakdown of cow manure, helping complete the natural nitrogen cycle that pastures need.
Sentence: Pastures can be treated to prevent larva from emerging from manure with applications of diflubenzuron or malathion. Both chemicals must be used with caution and a reentry interval of about a day. An easier solution would be to use a permethrin-based fly spray on horses or cows as needed. Systemic insecticides also exist for cattle, such as ivermectin and other pour on drenches. Be sure to always read and follow label instructions.