Doug Colwell, PhD, reminds us of the general rule in parasitology that states “in all breeds of cattle about 80 percent of the flies are on 20 percent of the animals.” Citing consumer concerns, he says non-chemical fly control is currently being researched. Horn flies are extra difficult to control. Insecticide ear tag use is common but often results in resistance in as few as three years.
Researchers at the University of Arkansas-Fayetteville and at Oklahoma State University have found through multiple horn fly studies that there are cattle breeds more susceptible to flies. Their research has found that the heritability of fly resistance is 0.58 percent.
Through selective breeding small herds of fly-resistant cattle have been developed including breeds such as, Angus, Hereford, Chianina and Charolais.
Source: FEED-LOT, May 31, 2022. Link.
The cattle that are more affected by flies will have offspring that are more affected as well. For horn fly control, the non-chemical options are limited and if you don’t want to use insecticides you can either breed cattle that are resistant or do nothing.” – Doug Colwell, PhD
Also see: Integrated pest management key to fly control, AHD, July 14, 2020. Link. When fly counts reach 200 flies per animal, the economic threshold has been reached, and animals will have significant weight loss. The economic threshold is the pest density at which producers should take action to manage the pest.