Peggy K. Powell, Ph.D., Board Certified Entomologist
February, 1995
Although the face fly, Musca autumnalis, is nonbiting, it is nonetheless a troublesome pest of cattle. The face fly's feeding activities, normally on secretions of the animal's eye and nose, often result in both annoyance to the animal and transmission of disease.
Face flies are 3/8-inch long, slightly larger than the house fly. A female face fly is slightly darker than a female house fly, but is otherwise almost identical. The male face fly's abdomen is orange with a black band down the center. The puparium or pupal case of the face fly is unusual in that it is white. An easy field identification characteristic is that face flies congregate in clusters of 20 to 100 on the faces of cattle.
Only the female face fly is a pest of livestock. Males spend their time perched on vegetation, awaiting mates. The males feed on plant nectar and on the liquid secretions of dung. Females feed on protein contained in eye secretions, nasal secretions, and saliva, not on blood. They feed only during the daytime, resting on fence posts or vegetation at night.
While the fly is feeding, the roughness of its sponging mouthparts irritates the cow's eye and increases tear production. Face fly feeding can transmit bacteria to the eye, increasing the likelihood of bovine pinkeye and Thelazia eyeworms.
In addition to feeding on facial secretions, face flies are sometimes facultative blood feeders. This means that although they don't bite cattle to obtain blood, they will feed on blood that oozes from scratches and other mechanical wounds.
The female face fly lays her eggs only in recently deposited (less than 15 minutes old) manure from grass-fed cattle. They do not lay eggs in manure piles around barns or in the trampled manure associated with feedlots.
Face fly larvae, or maggots, develop under the crust of the manure pat. When they reach maturity, they move into the soil next to the manure to complete their transformation to the pupal stage. The flies emerge as adults about a week later. Development from egg to adult requires from two to three weeks.
The face fly is active from early spring through late autumn. Although face flies prefer bright sunlight and do not enter buildings during the summer, in the fall adult face flies often seek out hibernation places inside structures.
The treatment threshold for face flies is five flies per animal. A population of 12 to 14 flies per animal will result in a decrease in grazing by about one hour per day. Twenty to 200 flies per animal is considered a heavy population. Heavy face fly populations can cause cattle to stop feeding and move into a shady location to escape the flies, resulting in reduced animal production. Dairy cattle will cluster together to reduce face fly attack, thereby increasing heat stress and reducing milk production.
Face flies are more difficult to control than horn flies because they spend less time on the animals than do horn flies. One of the most effective control methods is dust bags placed where cattle are forced to use them, such as on a mineral feeder or gateway. The dust bag should be placed low enough so that the cow must lift it up with its head.
Cultural control methods, such as cleanup of barn and barnyard manureCused effectively against the house fly and the stable flyCare not effective in controlling the face fly because it breeds in fresh manure.
Walk-through fly traps designed for control of the horn fly have been reported to occasionally trap face flies. In one study, between 2 and 13 percent of the flies caught in a walk-through trap were face flies. Research indicates, however, that this method is not reliable for consistent suppression of the face fly population in a herd.
Hall, Robert D. and Kathy E. Doisy. 1989. Walk-through trap for control of horn flies (Diptera: Muscidae) on pastured cattle. Journal of Economic Entomology 82:530-534.
Metcalf, Robert L. and Robert A. Metcalf. 1993. Destructive and useful insects, 5th edition. McGraw-Hill, Inc., 1073 pp.
Rutz, Donald A., Christopher J. Geden and Charles W. Pitts. 1993. Pest management recommendations for dairy cattle. A Cornell and Penn State Cooperative Extension Publication.
Williams, Ralph E., Robert D. Hall, Alberto B. Broce and Philip J. Scholl, eds. 1985. Livestock Entomology. John Wiley & Sons, 335 pp.
Programs and activities offered by the West Virginia University Extension Service are available to all persons without regard to race, color, sex, disability, religion, age or national origin. Issued in furtherance of Cooperative Extension Work, Acts of Congress of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Charles Morris, Interim Director, Cooperative Extension Service, West Virginia University.
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