Fly populations: Facts, control tips

In many animal production facilities, fly populations are continuing to increase. Before fly control can be effective, it is important to know which species of fly is causing problems. For Kansas cattle, there are three major species that can be pests for cattle on pasture --stable flies, face flies, and horn flies.

As for stable flies, both the males and females will bite and feed on the blood of both animals and humans. On cattle, they will most often accumulate on the legs causing the cattle to bunch up or stand in water. These tactics help prevent bites, but also reduce feeding which decreases weight gain.

There are currently no effective chemical means of controlling stable flies. They tend to develop in manure mixed with soil, hay or stray, typically in round bale feeding sites. As a result, steps should be taken to minimize hay waste and build up, or to spread waste.

Face flies are very similar to house flies in the fact that they have sponging mouthparts, but like the horn fly they develop in undisturbed cow patties. Face flies are the mechanical means of transporting pinkeye bacteria.

Pyrethroid ear tags are the best control for face flies, but the results are determined by the presence or absence of resistant populations. These flies overwinter in attics of rural homes and barns.

Both male and female horn flies bite and feed on the blood of animals, most often found on the shoulders, back and sides of animals. On hot days, they may relocate to the underside of the belly. Horn flies will stay on the animal until disturbed or until the female lays her eggs in fresh feces.

There are many ways to control horn flies, including ear tags, sprays, pour-ons, dusts, and rubs.

As for ear tags, there is no need to put two tags per animal. In fact, not every animal needs to be tagged for horn fly control. According to Ludek Zurek, medical and veterinary entomologist with K-State Research and Extension, tagging every third animal with one tag is good enough as horn flies move between animals and will eventually bite a tagged animal-killing the fly.

He also recommends rotating one year with a pyrethroid tag, two years with an organophosphate tag, one year with a pyrethroid tag, and so on.

Follow label direction for use and safety for all fly control products.

More information on fly control can be found in the K-State Research and Extension publication, "Managing Insect Problems on Beef Cattle." This publication is available from www.ksre.ksu .edu by searching for publication number C671 or by contacting the Bourbon County Extension Office.

Editor's Note: Delta George is a K-State Research and Extension agriculture and 4-H extension agent assigned to Bourbon County. She may be reached at (620) 223-3720.