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Buzz off: Strategies to manage flies on pastured cattle
With summer comes the inevitable for cattle producers: flies. Managing these pests can pose a challenge to producers and cause discomfort to cattle, so work ahead to create a management plan.
David Boxler, an entomologist at the University of Nebraska-Lincoln shares three ways to keep the most prevalent flies off pastured animals in the Midwest. Consider your pasture setup and the fly species present in your area when choosing the most effective strategy for your cattle.
Why bother with flies?
There are three common types of flies in the Midwest: horn, face, and stable. All three are blood-feeding, and depending on the species, each fly may take up to 30 meals every day. Blood loss can affect weight gains, grazing efficacy, and even milk production when fly numbers get high.
“It's been estimated that economic losses associated with the effects of horn flies can exceed $1 billion annually across producers in the United States,” Boxler says. “It is a significant pasture pest.”
Producers have many choices of insecticides to tackle their pest problems. Face and horn flies are the most similar when it comes to pest management and have the widest range of options, whereas stable flies can only be managed by manually applied insecticides.
Manual insecticide
Manual insecticide application requires the producer to administer the product either in the pasture or facility. It is the only effective method for preventing stable flies and is effective against face and horn flies.
In Boxler’s experience, many producers gravitate toward the pour-on method, which requires animals to receive the application from head to tail before being released to the pasture. The application lasts seven to 21 days and should then be repeated.
Using a conventional sprayer may be an effective solution for producers who often bring animals into a working facility.
“You can also use a mist blower to spray cattle right in the pasture,” Boxler says.
Getting your animals on the right spraying program can help to alleviate up to 80% of the fly population in the fields, according to Dan Schweers from Valley Industries.
Some sprayers can even be used to spray the pastures themselves. Schweers says the A1 Misters can apply insecticide directly to the grass and across the entire pasture with 50% fewer chemicals.
Boxler says a compressed-air application may be a good option for producers with smaller-scale operations. Like a paintball gun, producers shoot compressed capsules of insecticide onto their animals.
Self-applied insecticide
Some insecticide application methods rely on the animal itself to apply or ingest the product in the pasture. Several options are available through farm supply stores or online and are effective against face and horn flies.
Dust bags are a tool that have been used by farmers for pest management for approximately 40 to 50 years, Boxler says. As the animal hits a series of hanging bags filled with powdered insecticide, the powder spreads into the air and onto the animal, discouraging flies from settling on it. Dust bags are most effective in forced-used scenarios, where cattle must touch them to access an alleyway, food, or water.
Back rubbers and oilers are other methods for self-application. In addition to keeping flies away, these tools satisfy a calf’s instinctive need to scratch, making this a two-for-one, Boxler says. Oilers use a brush, mop, or curtain that allows cattle to apply insecticide to themselves. that allow cattle to apply insecticide to themselves. This is also most effective when placed in a force-use situation.
Another effective tool is a feed-through insecticide, often fed via an additive to a salt or mineral block. This travels through the animal and kills the fly egg and larvae where they are born – in the manure.
One such feed-through is Altosid IGR, an insect growth regulator incorporated into the cattle’s mineral or feed. Once flies lay their eggs into the manure, the Altosid IGR prevents pupae from developing into biting adult flies.
“This is a horn-fly-specific control with no impact on birds, wastewater, soil, plants, beneficial insects, or human health,” says Mark Upton, Senior Director of Sales, Feed Additives, Central Life Sciences. “It’s the ideal choice for the environmentally responsible producer.”
Altosid IGR can provide season-long fly prevention, as most feed-through insecticides work as long as the cattle consume it. Effective control requires consistent feeding, Upton says, which can be achieved by following the labeled feeding rate, keeping feeders full, monitoring regularly, and keeping a log of consumption.
Boxler says many producers like the feed-through method, as it requires them to check-in and replenish it when checking fields.
Natural methodology
In the 1930s, Willis Bruce, an entomologist with the USDA, designed a walk-through fly trap that did not contain any insecticide. The design was a wooden structure that animals could enter from both ends, with strips of carpet or canvas hanging down for the animal to walk through.
The idea was that as the animal walked through, the canvas would knock the flies off. Attracted to the natural light, the flies would move to the top of the structure and get stuck.
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“It’s a design that many producers who like to raise their cattle organically or naturally are gravitating to,” Boxler says.
The walk-through fly trap is also most effective if used in a force-use scenario.
Boxler suggests combining methods to keep livestock as fly-free as possible. He also recommends rotating insecticides to prevent flies from building up immunity.
