August 5, 2012

Flies not just a nuisance

Peter Hagar, Cornell Ag Connection

---- — Have you ever been bothered by that annoying fly that buzzes around you head like a miniature dive bomber? Just imagine how a cow feels with dozens of flies buzzing, biting and aggravating it all day long. 

Whether they are out on pasture or in a free-stall barn, flies can cause undue harm to dairy cattle and other livestock and can cause off-farm concerns. Did you know Cornell University’s Veterinary Entomology Program has developed a highly effective integrated program to help producers minimize fly problems, protect animal health and net profitability? Did you know Cornell University has the only Veterinary Entomology Program in the northeast?

As concern related to pesticide use increases, Integrated Pest Management (IPM) for livestock pests becomes more important every year. The summer season can expose fly-management issues on individual farms yet provides educational opportunities to avoid problems, too.

Have you seen more flies on farms even after insecticide use? This could likely indicate presence of insecticide resistance, an increasingly common problem on New York livestock farms. Add to this, there are fewer insecticides currently on the market that are registered for livestock use. These issues and others have increased concerns over options available for fly control. What is one to do? An integrated approach is the only effective means to keep fly populations at manageable levels.

Another interesting fact is that there are several distinctly different livestock flies that affect cattle, goats, sheep and horses. Blood-sucking flies, such as horn flies, stable flies, horse flies and deer flies, can cause severe stress and annoyance to cattle. “Fly worry” can lead to decreased weight gain and milk production because cattle spend time trying to avoid and remove flies rather than feeding. Fly bites may also cause hide damage and spread viral, bacterial and parasitic diseases. Face flies and house flies are mainly a nuisance to cattle, but face flies can cause severe eye irritation and contribute to the spread of Pinkeye, an infection of the eye.

Identification of these different flies is made by observing their size, location on the animal and even their orientation while resting or feeding. As named, face flies primarily congregate around the eyes and nostrils feeding on the mucosal secretions. Stable flies are almost always found facing head up on the lower legs of animals and only when feeding. Horn flies congregate on the back and sides and feed in a head-down orientation. With proper identification, appropriate measures can be taken to control and prevent the populations from becoming detrimental to the health and production of your livestock.

Dairy farms already know that fly control is an important management task. The Department of Agriculture’s Grade A Pasteurized Milk Ordinance specifies the responsibility of dairy producers to conscientiously reduce fly populations on their farm. Dairy and health inspectors are becoming more conscientious of fly infestation on farms. With fewer pesticides labeled for flies in dairy barns, alternate methods of control and prevention are becoming more important.

Over the last decade, the Cornell Veterinary Entomology Program has conducted a great deal of research developing new information to better manage livestock flies in and around confinement facilities and for animals on pasture. Some important areas of their research include insecticide resistance with house flies, biological control of house and stable flies, evaluation of physical control methods such as giant sticky traps in barns, several types of fly traps on pastures, ecology and importance of dung beetles in manure pats, and management of cattle lice and mange mites.

For more information on livestock IPM, see the New York IPM Program website at and the Cornell Veterinary Entomology website

In order to share the latest fly-management information with producers, Cornell Cooperative Extension of Clinton County is offering a barn fly IPM workshop on Tuesday at 1 p.m. at the Dimock Farm in Peru. This farmer and large-animal veterinarian oriented farm meeting will provide an overview of fly management issues and include a walk-about to illustrate fly management opportunities. Sound interesting? If so, or if you would like more information, call the Extension office at 561-7450 or email to let me know that you plan to attend.

Peter Hagar, agriculture educator, Cornell Cooperative Extension Clinton County, 6064 Route 22, Suite 5, Plattsburgh, 12901. Phone 561-7450, fax 561-0183 or email