With fly season approaching, now is the time to evaluate and refine your fly management plan for 2025.
“If your 2024 control efforts underperformed, consider adjusting your approach,” says David Boxler, Nebraska Extension livestock entomologist. “The best control method will depend on several factors including efficacy, cost, convenience and your current herd management practices.”
He also reminds producers that horn flies can migrate from neighboring untreated herds, masking the effectiveness of your efforts and increasing fly pressure. For this reason, Boxer recommends a comprehensive, integrated fly control.
The horn fly is one of the most damaging pests of pasture and rangeland cattle across the U.S., Boxler says in a recent “UNL Beef Watch.”
“Adult horn flies are blood-feeding insects that take an average of 30 blood meals per day,” he says. “Their populations can build rapidly and often exceed the Economic Injury Level defined as 200 flies per animal. Once fly numbers surpass this threshold, cattle experience reduced weight gain and milk production due to fly-induced stress and altered grazing behavior.”
Observing your cattle during summer months is key to detecting fly pressure. Boxler asks, “Are they constantly tossing their heads, swishing their tails or twitching their skin?”
These signs of fly irritation indicate a more effective control strategy might be needed.
“If you are seeing flies, ticks, lice or insect damage to your cattle herd, we know there is an economic impact; however, that impact can become far greater than production or weight gain loss alone,” says Ashby Green, DVM, Neogen senior technical services veterinarian. “Insect pressure affects grazing patterns of cattle, it affects their comfort and it can lead to health issues. Some of those health issues can be definite, such as anaplasmosis.”
The vectors responsible for spreading anaplasmosis include horse flies, stable flies and ticks. This condition has been reported in most states across the U.S., while the disease has been recognized as endemic throughout the South and several Midwestern and Western states.
“With horn flies, we’re looking at mastitis risk, so that’s going to impact both dairy cattle and also our cow-calf operations,” says Jonathan Cammack, Oklahoma State University assistant professor and state extension specialist. “A lot of times, horn flies will feed on the udders of the animals, and they transfer the Staphylococcus aureus bacteria because they land on the manure, then they go back to the animal to feed and bring those bacteria with them.”
Several other conditions are propagated by flies or ticks, including pinkeye, which can be spread by face flies and causes inflammation and ulceration of the eyes. Pinkeye-affected calves are, on average, 35 lb. to 40 lb. lighter at weaning compared to healthy calves, according to a University of Kentucky report.
Cammack says that due to flies, “We’re looking at probably $6 billion in losses annually to U.S. cattle production, and that encompasses everything from actual loss in production due to decreased weight gain or decreased milk production, veterinary needs associated with treatment of cattle with exposure to pathogens from some of these insects, and then also the control measures associated with managing those individual fly species.”
Ticks present economic risks as well. Cammack says that during a 100-day growing period producers can see a decrease in total weight gain in calves by about 20 lb. For stockers, over that same 100-day period during the summer months, they can experience a decrease in weight gain by about 60 lb.
“With what current prices are, 60 lb. could translate to a significant amount of money returned when we’re talking about the few dollars that it might cost for some tick control,” he says.
Controlling flies and insects: Tips to implement
Now is the time to take steps to control flies and ticks, as populations emerge with the warmer weather.
In “Stopping Flies in 2025: Tips to Battle These Economic Pests,” Cassandra Olds, Kansas State University Extension entomologist, shares four steps to controlling flies
- Know what flies you’re dealing with.
- Reduce populations.
- Eliminate breeding grounds.
- Consider chemical control options.
Similar to Olds, Green recommends using a multi-pronged approach to insect control. Fly tags, feed-through insect growth regulator (IGR) products, pour-ons, back rubbers and dust bags can help diminish the population. A pour-on with an IGR destroys the larval development in flies and greatly reduces the fly population. For ultimate control using a pour-on, look to a unique combination of actives within one solution that includes an IGR, an adulticide, and a synergist that supplies relief to cattle from infestations and provides producers with a reliable solution that helps minimize handling, time and labor costs.
“Both back rubbers and dust bags can be highly effective if managed correctly. Keep in mind, when these are put out to withstand the elements, including moisture and rain, it’s key to keep the dust fresh or the oil recharged in your back rubbers. Otherwise, they will diminish in their ability to control flies quickly,” Green advises.
Cammack stresses the importance of accurate dosing by the individual animal’s weight and following label guidelines.
To best control flies and insects on cattle operations, “the easy and effective way is the best way,” Green summarizes. “It’s up to you and with the help of your veterinarian to help create that combination.”
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