The necessity for a fly control program for beef herds is inevitable and if you haven’t started a program in your herd, now is the time. The two major species of flies 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 animal losses to the US beef industry of $700 million. Tests have shown that the annoyance, irritation, and blood loss caused by flies can reduce weaning weights of calves nursing fly infested mother cows by 12 to 14 pounds; average daily gain of grazing yearling steers may be reduced 12 to 14 percent, or as much as 30 pounds, during the grazing season. Both face flies and horn flies annoy cattle, resulting in reduced grazing time and increased energy expenditure.
The adult horn fly, which is about one 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. They are normally found on the animal’s back, but may migrate to the sides and the belly as the temperatures increase. They are weak fliers, but may be carried great distances by high winds. The females leave the animal only to lay eggs in fresh cow manure, where they hatch into larvae. The life cycle is completed in eight to forty-five days depending on temperature and humidity. The best methods of fly control are the integrated approach, using several different methods and insecticides for a longer lasting, more effective fly control program. For more information contact your CooperativeExt.Center.
Source: Beecher Allison, retired NCSU Beef Cattle Specialist