Cattle Fly Control Prevents Losses

Flies can be a pest throughout the year for cow herds. Using good control methods at the right time helps with return on investment.

North Dakota State University Extension veterinarian and livestock stewardship specialist Gerald Stokka says having a good pest-management strategy is key to helping provide effective control.

"Timing and the type of pest control depends on the species of flies," he advises.

Horn and face flies are usually seen in early summer and won't reach economic thresholds for applying control until midsummer. Horn flies are gray and look like small houseflies.

"The constant biting causes cattle pain and stress, and can reduce the cattle's weight gains by as much as 20 pounds," Stokka adds.

Face flies look like large, dark houseflies. These are nonbiting flies that feed on animal secretions, plant nectar and manure liquids. They are responsible for infecting the eye and causing pink eye in cattle, and usually peak in late summer.

The stable fly has circular markings that distinguish them from horn flies. These feed on blood, biting on the abdomen and legs, and are difficult to control.

There are several different kinds of fly control, and some may work better than others in certain environments. An effective and convenient way to deliver horn fly control is by feeding cattle a mineral containing an insect growth regulator (IGR), which works for all classes of cattle. When IGR is present in the manure, it prevents pupae from developing into adult flies. This should be fed 30 days before the last frost of spring through 30 days after the first frost of fall to ensure cattle are consuming the target level.

Ear tags containing insecticides that are slowly released into the animal's hair by movement can be a good option for later in the summer. Follow label directions for what age cattle can be tagged and to ensure good coverage.

Pour-ons and on-animal sprays are other control options. These are typically applied directly on the animal's back line, and the chemical is absorbed and circulates through the animal's system. These can control flies for up to 30 days before requiring another application.

Dust bags, back rubs and oilers are effective for forced-use situations. These should be placed where cattle enter frequently, such as water or feeding sites. Powder or liquid is used as an insecticide and should be checked frequently to make sure the insecticide is stocked.

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-- Jennifer Carrico can be reached at jennifer.carrico@dtn.com

-- Follow Jennifer on social platform X @JennCattleGal

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