Every spring horn flies are guaranteed to steal production, pounds and profits. Early control is key.

There are many products on the market to control flies: insecticide ear tags, pour-ons, insect growth regulators (IGRs) mineral supplements, oil slicks and insecticide sprays. While many researchers say using a two-prong approach is beneficial, IGR products provide reliable and economical control.

“For cow-calf herds, IGR products provide about 20 lb. of extra weaning weight on calves,” says Kevin Glaubius, director of nutrition and technical sales for BioZyme Inc., makers of VitaFerm.

Insect pressures of more than 200 flies per animal can cause up to a quart of blood loss, reduced grazing activity and an increased risk of anaplasmosis.

“If cows are constantly losing blood, it puts a strain on her metabolic systems,” says Ted Perry, nutritionist with Purina Animal Nutrition. This slows other natural process in the body, such as milk production and weight gain.

Having an aggressive control strategy from early spring through fall (30 days before the last frost) will help break the insect cycle and control any flies that overwinter in the pupal stage.


Editor's Note: This article originally appeared in the April 2017 issue of Drovers.