Face flies, Musca autumnalis, are a pest of cattle throughout the United States, except for the Deep South, Arizona and New Mexico. These flies are slightly larger and similar in appearance to house flies.
Face flies feed on fresh rangeland feces, which generally limits their effect to nonconfined cattle. Cattle confined near pasture may also be infested.
Typical of other species of nonbiting flies, face flies feed on liquid substances. Face flies feed particularly around the eyes, nose and mouth, and are thought to be spreaders of bacterial organisms that cause pink eye. The mouth parts of these flies irritate the eyes, creating an environment suited to bacterial growth. As the eye becomes irritated and begins to weep, it attracts more and more flies, adding to the irritation and opportunity for spread of infection.
Control of face flies is difficult because individual face flies spend relatively little time on the animals and due to problems in applying insecticides to the eyes, face and nose of cattle.
Buffalo gnats (Simuliidae), known most commonly as black flies, can be significant pests of cattle, damaging performance and causing disease. These insects are common inhabitants of north-temperate and subtropic areas. Black flies are often seen in swarms where strong or swiftly flowing streams provide well-aerated water for larval development. Females require blood for ovarian development.
Another group of biting gnats from the Ceratopogonidae family is a cattle pest. This group includes insects known as midges, sandflies and punkies. Protecting cattle from gnats is very difficult. Most control measures focus on the environment.
Heel flies are the parents of cattle grubs. These robust flies hover and dart around the legs of cattle during the winter in the South, early spring in Central states, and spring through summer in Northern states. They superficially resemble honey bees. They do not feed as adult flies and individuals live for only about a week. Heel flies do not land on cattle, but the females hover close to the heel or leg as they attach eggs to individual hairs on the animal. The ovipositing action apparently tickles the animals and this, along with the buzzing noise made by the flies, causes cattle to run wildly with their tails in the air.
The eggs hatch within a week, tiny larvae crawl down the hair and enter the cow’s skin, and internal migration begins a cycle that will end with large grubs in the animal’s back.