Face flies: tough to manage pests

© 2018-The Weston Democrat

Agriculture Topics

The face fly is a tough-to-manage pest of pastured cattle.  In addition to the irritation it causes while feeding, this fly can play a major role in the spread of the strains of the bacterium that causes pinkeye within and between herds.
As common as this insect pest is today, it is hard to imagine that in our lifetime – some of us anyway – this fly did not exist in the United States.  
During 1950-1951 the face fly was introduced into Nova Scotia from Europe, and by 1953, was found in the northeastern U.S.  
By 1960, it had spread to 26 states in the northeastern quarter of the U.S.   Today, face flies are better able to reproduce, and are more of a problem in higher rainfall areas, like West Virginia.
Female face flies visit cattle for short periods of time to get the protein they need for egg production.
Sources include tears, mucus, and saliva. Their sponging mouthparts have small, abrasive teeth that scratch tender tissue around the eye to stimulate tear flow; the tears are then blotted up by the fly’s specialized mouthparts.
Cattle reacting to face fly annoyance interrupt fly feeding which means that the insect may have to visit several animals to get a complete meal.
Face flies may pick up the pathogen from an infected animal and carry it to uninfected animals as they continue to feed.
The pathogen can survive on a face fly for three to four days, increasing the potential spread of the infection.
While the role of face flies is important, other eye irritants, such as tall grass, pollen, and bright sunlight also injury the eye and can play a role in spread of this disease.
Face fly control is an important part a heard health program but this is a tough insect to control because: 1) face flies spend very little time on animals and 2) they are mostly on the face which is difficult to keep treated with an insecticide.
In addition, face flies may move several miles, so in-flight of flies from nearby herds can compound control problems.
Daily access to forced-use dust bags or oilers with fly strips or bullets generally provide good fly control because they are used regularly by all animals in the herd.
Some insecticide ear tags also can reduce face fly numbers significantly.
Check regularly to make sure oilers and dust bags are charged and that they are dispensing insecticide properly.

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