Vet’s Voice: A season of flies
July 18, 2014
Summer is definitely upon us. Our area had had plenty of timely rains, but I know some of you have not been so lucky. The grass is doing great, but the warm, wet weather had been terrific for flies. The populations have exploded in the last few weeks.
Heavy infestation of flies causes great discomfort for the both the cows and calves. The irritation causes the animals to spend more time fighting flies than eating. This results in decreased milk production and thereby less weight on your calves at weaning.
There are several types of flies causing problems in our area:
Face flies of course are found primarily on the animals face. They live on the secretions (tears) produced by the host. These insects are best controlled by spraying or dust bags which apply insecticide directly to the face. Other than irritation they are a primary vector in the transmission of pinkeye. Anytime you are dealing with pinkeye problem, you must address the fly populations in the herd.
Horn flies are commonly found on the neck and back of cattle. These flies actually bit the host animal and consume the host's blood. Many times a bull's neck will be totally covered with thousands of these pests. Systemic controls are useful on these insects. Injectable antiparaciticides are useful in prevention and treatment. One new long duration product appears to have a prolonged effect on fly populations. These results are merely testimonials and not scientifically proven, but it may be worth a try in your herd, because most of other duration products now available lose their effect when the fly populations increase because they have surpassed their window of effectiveness. Sprays and pour-ons are also effective, but we only see duration of two to three weeks rather than the thirty days most products claim. You will probably need to repeat these products on a two week basis. Products which pass through the cow into the manure patties are also very useful. If your herd is relatively isolated, you will have better success. Remember these flies may travel several miles in the wind and if your neighbor is not using this product you will inherit their flies. Dust bags and back rubbers are also effective in areas where the cows congregate – mineral feeders, watering areas, creep feeders.
This year we seem to be seeing a lot more flies which appear to be house flies. They tend to reproduce in rotting vegetation and we have more than normal with the floods we have had. The problem is these pests seem to prefer the legs of the animal. That means products need to be applied to the legs of the animal as well as the face and back. Most of our delivery systems do not allow this application. The best way to control this menace is to clean up decaying vegetation. Premise sprays may also be useful in this scenario. Simply spray the area where the flies are hatching to decrease the problem.
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Summer has always provided populations of external parasites. This year appears to have been a great year for fly production. Consult your veterinarian, extension specialist or nutritionalist and devise a program to fit your operation. Remember to keep the dust bags and back rubber charges and plan to reapply herd treatment as population increase every several weeks. Careful Attention to detail will produce higher calf weights this fall. With these record prices these extra pounds will easily pay the cost of control.