For grazing cattle in the Southeast, warmer weather often signals the onset of those annoying flying pests during the months commonly referred to as “fly season.” In our area, fly season typically runs from the last frost in the spring to just after the first frost in the fall. These external parasites can be quite costly in terms of lost production, treatment costs, and disease transmission.
The three major species for concern are houseflies, face flies, and horn flies. Of these, horn flies are by far the most costly and are often confused with face flies. The horn fly however, is a small, black fly, about the size of a grain of rice, spending the majority of its life on the back, shoulders, and belly of its host, feeding in a head-down position.
Horn flies emerge in the spring when average daily temperatures reach 65 degrees for a period of at least two weeks. Having only a 10-to-20-day life cycle, the adult female leaves her host only long enough to lay eggs in fresh manure pats. Each female can lay up to 500 eggs during her lifespan, allowing populations to increase at a rapid pace. Around 200 horn flies per animal is the documented economic threshold, and when left uncontrolled, as many as 4,000 per animal may be observed when numbers peak. Each horn fly takes 20 to 30 blood meals per day by piercing the animal’s hide. The ensuing pain and irritation cause cattle to alter their grazing patterns and expend valuable energy attempting to dislodge the flies. Decreased weight gain and loss of milk production are the end result.
USDA research estimates the horn fly costs U.S. cattle producers nearly $1 billion per year in lost production. Fortunately, stockmen have several effective options for controlling horn flies and minimizing their associated losses. Insecticide ear tags, pour-ons, back rubbers treated with insecticides, premise sprays, and feed-through insect growth regulators (IGRs) can all be of use in keeping fly numbers in check. The most convenient of these is a cattle vitamin/mineral supplement containing an IGR. This method eliminates the stress, labor, and expense of handling cattle, while allowing them to spread the horn fly control as they graze.
Feed-through IGRs control horn fly populations by preventing the eggs from developing into adult flies, therefore greatly decreasing the numbers. The compound is consumed and passes unaffected through the animal’s digestive tract, ending up in the manure pat where it kills the fly larvae. For successful fly control, any of these products must be consumed daily in adequate quantities such that all manure contains effective levels of the IGR.
By using a Co-op Fly Control mineral as part of a complete fly control program, producers can gain significant benefits beyond just fly control. Forages consumed by grazing cattle can be deficient in several essential minerals regardless of season. Phosphorus, copper, zinc, and selenium all play vital roles in growth and reproduction of beef cattle and Co-op Fly Control minerals bridge the gap between the animal’s requirements and those provided by the forage.