Proper use of insecticide ear tags can help protect your cattle from face flies (pictured) and horn flies. (Photo by Dave Boxler, University of Nebraska–Lincoln Extension)
Proper use of insecticide ear tags can help protect your cattle from face flies (pictured) and horn flies. (Photo by Dave Boxler, University of Nebraska–Lincoln Extension)

As we transition into spring and before livestock producers turn cattle into pastures, selecting this year’s fly-control program should be considered.

A thought to ponder: Did your fly-control program work last year? If not, now is the time to consider something different.

There are many fly-control options and strategies available to livestock producers to help manage the three fly species that economically impact grazing cattle: the horn fly, face fly and stable fly.


Horn Flies

Economic losses associated with horn flies are estimated at more than $1 billion annually in the U.S. Horn-fly feeding causes irritation, blood loss, and decreased grazing efficacy; reduced weight gains; and diminished milk production in mother cows.

Horn flies have also been implicated in the spread of summer mastitis.

There are many insecticide-control methods available to manage horn flies.

Insecticide ear tags and strips are a convenient control method; however, many horn-fly populations exhibit a degree of resistance to the pyrethroid class of insecticides. Because of this, the recommended management practice to maintain horn-fly control is to rotate insecticide classes annually.

Back rubbers and dust bags are also an effective way to reduce horn-fly numbers if cattle are forced to use them.

Animal sprays come as ready-to-use or are diluted with water before applying. Sprays can be applied with low-pressure, low-volume sprayers on ATVs or by using high-volume, high-pressure sprayers. Animal sprays can provide several weeks of fly control, and will require multiple applications through the fly season.

Pour-ons are ready-to-use formulations (RTUs) applied along the back line of cattle at a dose based on body weight. As a rule, they provide several weeks of fly reduction, and must be reapplied through the fly season.

Oral larvicides (feed additives) are insecticides that are incorporated into mineral blocks, tubs or loose mineral. The insecticide is passed through the animal’s digestive system into the manure, where it kills fly larvae.

Oral larvicides are effective when consumed in sufficient quantities season-long. Adult fly numbers may appear unaffected if cattle consuming feed additives are pastured close to an untreated herd allowing for horn fly migration. An untreated group of cattle may provide enough horn flies to keep fly numbers above the economic threshold for both treated and untreated cattle. This is why it’s important to have a ranch- and farm-wide plan and to also work with neighbors.


Face Flies

Achieving adequate face-fly control can be difficult because of their habit of feeding around the face and the significant time they spend off the animal.

Control is maximized when cattle receive daily insecticide applications by either dust bags, oilers, sprays or an insecticide-impregnated ear tag. Ear tags should be applied at the label-recommended rate. Both cows and calves must be treated if control is to be achieved.

Pinkeye vaccines are available and should be considered if face flies and pinkeye have been a recurring problem. Currently, commercial and autogenous pinkeye vaccines are available. Please check with your veterinarian about the use of these products in your area.


Stable Flies

The only adult-management option available for the control of stable flies on range cattle is the use of animal sprays. Sprays can be applied using a low-pressure sprayer or a mist-blower sprayer. Weekly applications of these products will be required to achieve reduction in fly numbers. Clean-up of wasted feed at feeding sites can reduce localized fly development. If sanitation is not possible, these sites can be treated with a product to kill developing maggots.

When applying any insecticide-control product, please read and follow label instructions.


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