Learn how to minimize the impact flies have on your herd.
By: Edward Pruss, Penn State
For most beef producers, the yearly calving season has been completed and the important task of getting beef cows and beef heifers bred is now the main focus for most beef cattle producers.
Another important focus is the successful control of different flies as the beef herd takes advantage of green pastures and warmer summer temperatures.
There are at least three fly species that can economically impact beef cattle production. These species include: the horn fly, the face fly and the stable fly. The successful control of these flies can mean extra dollars earned for the beef producer. The beef herd can remain productive because cows, heifers, feeder calves and herd bulls can remain comfortable and somewhat stress-free in their summer – time pasture feedlots.
The horn fly is a blood feeding pest of pastured beef cattle. This fly is responsible for losses of beef cattle performance in the millions of dollars each year. When horn fly numbers are high, beef cattle experience a high level of annoyance and blood loss. The end result of high horn fly populations is decreased milk production, reduced weight gains, changes in grazing patterns and cattle bunching together.
The threshold injury level, for horn flies, is about 200 horn flies per beef animal. Multiply this number times the number of beef cattle in your beef herd, and, one will appreciate the need to control the horn fly population in any beef herd.
The horn fly can usually be found on the shoulders, back and belly region of beef cattle. A typical horn fly will take some 20 to 30 "blood meals" each day. The only time they leave a beef animal is when the female horn fly deposits eggs in fresh cow manure. The complete life cycle, from egg to adult, can usually be completed in 10 to 20 days, during warm summer conditions. Without any type of control, multiple generations of horn flies can impact any beef herd with measurable economic losses.
A variety of horn fly control measures are available with good results. These horn fly controls include: dust bags, back rubbers (oilers), animal sprays, oral larvacides (feed additives), pour- on insecticides and insecticide impregnated ear tags. Sometimes a combination of two or more of these horn fly control measures is needed to achieve a reasonably high level of control of horn flies.
The face fly resembles the house fly. It is a non-biting fly that feeds on animal secretions. The adult female face fly typically clusters around a beef animal’s eyes, mouth and muzzle, causing a high level of discomfort and annoyance to the beef animal. Face flies can be vectors of Moraxella bovis, the principal cause/agent of bovine pinkeye or infectious bovine keratoconjunctivitis. Pinkeye is a highly contagious inflammation of the cornea and conjunctiva of beef cattle. If coupled with the infectious bovine rhinotracheitis (IBR) virus, M. bovis can cause a much more severe inflammatory condition.
Controlling face fly populations is a key strategy to reduce potential pinkeye problems. Fly control methods described in the discussion of horn fly control can be used against face flies. Insecticide ear tags tend to provide a higher level of face fly control during the summer months. It’s very important to apply two of the insecticide ear tags to the ears of both adult beef cattle and younger feeder-size beef cattle as well. These insecticide ear tags can give from three to four months of face fly control.
Stable flies can be an additional pest of beef cattle out on pasture. Stable flies typically feed/bite the legs of beef cattle. The normal reaction to stable fly biting is the "stomping" of feet and switching of tails. Some other avoidance behaviors, observed when stable flies feed or bite beef cattle, is standing in farm ponds or other water sources, lying down with their legs tucked underneath their body and the bunching or crowding of beef cattle in the corners of a pasture.
The economic impact, of stable flies on a beef herd, is the loss or reduction in the average daily gains normally achieved by feeder cattle in a pasture or feedlot setting.
The stable fly female lays eggs in rotting, spoiled or fermenting organic matter. The addition of animal manure, moisture and soil can result in a medium ideal for stable fly populations to grow and hatch into stable flies that can cause problems for beef herds.
Some common stable fly breeding sites would include: feed bunks and feeding aprons, under fences and near stored hay and other forages.
Stable fly control, in pastured beef cattle, is achieved by using animal sprays such as permethrin and/or pyrethroids. These animal sprays tend to offer a "quick kill" of the stable flies, but, a somewhat short residual time of control.
It is also very important to clean-up potential breeding sites and to follow good feed bunk management in beef cattle feedlots.
A variety of flies, including horn flies, face flies and stable flies, can have a major economic impact on beef cattle out on pasture or in a confined feedlot. Beef cattle producers are strongly encouraged to assess their beef cattle herd for fly pressure and to do a good job of controlling these pests. Good, summertime fly control can be an important piece of the beef cattle enterprise success. It can also help to maximize the yearly economic return thru increased beef sales and production and the beef herd’s overall welfare.
In addition, all beef producers are strongly encouraged to follow all labeled directions and to observe and follow all and any precautions when using dust bags, back rubbers (oilers), animal sprays, oral larvacides (feed additives), pour-on insecticides and insecticide impregnated ear tags to control flies in their beef cattle operations.
Note: Excerpts from "Controlling Flies On Pastured Cattle", by David J. Boxler, Extension Educator, West Central Research and Extension Center, University of Nebraska – Lincoln, North Platte, Nebraska, May, 2013.