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Fly-control mineral is foundation for effective control

Royce Towns, TFC Nutritionist 3/25/2020

The pesky little thieves don’t show up wearing lone ranger masks and carrying six-shooters. But these sneaky varmints are stealing from you in just as brazen a way as any bank robber on the six o’clock news.

They seem like such little things. But it doesn’t take many to make cattle miserable and rob you of profits in terms of lost production, treatment costs, and disease transmission. I’m talking, of course, about the nuisance flies that will soon be flocking to your cattle herd. Fly season begins shortly after the last frost of spring and lasts until just after the first frost.

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 can be identified as 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 fly pupae overwinter in manure pats and emerge in the spring when average daily temperatures reach 65o F for a period of at least two weeks. Having only a 10-20 day life cycle, the adult female leaves her host only long enough to lay eggs in warm, fresh manure. 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 in early summer. Each horn fly takes 20-30 blood meals per day by inflicting a piercing bite through 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. This behavior translates into reduced rates of gain in stocker cattle and decreased milk production and lower calf weaning weights in brood cow operations.

In terms of total production losses, USDA research estimates the horn fly costs U.S. cattle producers nearly $1 billion per year.  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 interrupts the life cycle of the fly, preventing development into the adult stage. For optimum fly control, these products must be consumed daily in adequate quantities such that all manure contains effective levels of the IGR.

In addition to fly control, a complete vitamin-mineral supplement containing a feed-through insecticide provides additional nutrients necessary for grazing cattle to get the most from pastures. Forages 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 help bridge the gap between the animal’s requirements and those provided by the forage.

For most effective results when using Co-op fly-control minerals, begin feeding before flies appear in the spring. Offer minerals in covered feeders and monitor consumption throughout the summer, adjusting placement as needed. And finally, when beginning an IGR program mid-season, use an appropriate spray or pour-on to quickly reduce the number of adult flies.

For more information about effective fly management programs, visit with your local Co-op feed specialist.

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