Remember Fly Control For Cattle This Summer

   Fly infestations of cattle are a real concern during the summer months. Typical flying insects that can cause problems in Illinois include stable flies, house flies, horn flies, face flies, mosquitoes, horse flies and deer flies. The two major species that cause the most serious decreases in beef production and require the most control efforts are the horn fly and face fly. The horn fly alone is estimated to cause $700 million in animal losses to the U.S. beef industry.
   Cattle pests, such as flies, cost beef producers in both treatment expenses and lost production. The discomfort to livestock and economic effects of heavy fly populations are easily noticed. Economic losses occur because feeding by horn flies, stable flies, horse flies and other bloodsucking flies mechanically transmits several disease organisms and causes irritation and physiological changes that decrease weight gains. Effective control measures will allow increases in profitability in beef cattle operations.
   The adult horn fly, which is about half the size of a house fly, has piercing/sucking mouth parts and feeds on blood and tissue fluids of cattle. They spend most of their adult life on cattle and feed 20 to 40 times a day. Losses begin to occur when there are 200 to 250 flies present. If young animals or cows have this many or more flies, then treatment will result in increased weight gains.
   The face fly is about the size of a house fly. They are non-biting and prefer to be on the face and consume the secretion from the eyes and nostrils. These flies avoid entering dark places, such as a barn, while on the animal. They are present on cattle only about 10 percent of the time and may be found resting on fence posts, trees, bushes and other objects the other 90 percent of the time. Because they spend so little time on the animal and do not feed on blood, they are much harder to control than horn flies. They are particularly important because they serve as mechanical carriers of the causative agent of pinkeye in cattle --- infectious bovine keratoconjunctivitis [IBK] caused by the bacterium Moraxella bovis --- and because they damage the cornea of the eye during feeding, thus allowing a port of entry for the pinkeyecausing organism.
   Cattle can tolerate low fly populations. When fly populations reach 100 to 200 per animal, it is economically advantageous to begin a control program. There are several methods of fly control such as insecticide sprays, dusts, pour-on products, oilers, dust bags, ear tags, oral larvicides in minerals and blocks, and controlled release boluses. All of these methods are effective and have a place in the control program; however, the best defense is usually an integrated fly control program.
   When making decisions about fly control, realize that there are many effective programs. Develop a program that is cost effective and most convenient for your operation.
   Here are several things to keep in mind: 1) Plan ahead for insecticide and ear tag purchases; fly season always comes, even if delayed by cool weather or rain; 2) Consult with your herd veterinarian regarding active ingredients in products and their record of effectiveness in your area; 3) Always follow instructions, warnings and precautions because these products can be toxic to you, your children, pets and others working with them around the chute; and 4) Follow label withdrawal times and keep records of treatment dates, products and lot numbers. Δ
   DR. TERESA L. STECKLER: Extension Specialist, Animal Systems/Beef, University of Illinois

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