Sarah McNaughton, Editor, Dakota Farmer
June 4, 2024
4 Min Read
SHOO FLY: Flies that feed on blood and secretions are the pests that can cause the greatest economic impact, according to University of Minnesota Extension. Photos by Sarah McNaughton
Those pesky flies buzzing around cattle are more than just a nuisance. Flies can impact weaning and lactation rates, stress cattle, and spread disease. Finding the best method for fly control takes a bit of strategy.
University of Minnesota Extension shares that the most common culprits on farms in the Northern Plains are:
stable flies
houseflies
face flies
horn flies
Most can be categorized as “premise flies” or “pasture flies.” Stable flies and houseflies are considered premise flies, and are found in confined areas like barns, where they reproduce in organic matter such as bedding or manure.
While houseflies feed on mouth and eye secretions, stable flies feed on blood and cause stress in cattle.
Stable flies are found often on cattle’s legs, where they can cause animals to stomp their feet, twitch their tails and bunch up trying to keep the flies away. U-MN says these flies can result in reduced production.
To keep these flies at bay, start with sanitation. Remove breeding sites such as old hay or rotting grain, manure piles, feed or mixed rations, and other organic matter. While a seasonal cleaning can be beneficial, consistent upkeep is key to a successful management plan.
After ensuring that your barns are in top shape, scout for signs of flies next. Look to see where maggots may be present to find additional places that may need some sanitation. Sticky traps are another way to monitor fly populations to determine if chemical management is beneficial.
Pasture fly control
Pasture flies, such as horn and face flies, are often seen outside of confined spaces, breeding in cow pies in pastures or pens. These two species can cause major economic losses in cattle, through disease transmission and lower weight gain.
Horn flies are blood feeders, and their presence will cause tail switching, head throwing and bunching in animals. They are found along the body of the cow on the back, sides and belly.
The management threshold for horn flies is about 200 flies per head of cow, according to U-MN. The flies substantially reduce weight gain, resulting in major economic losses for the operation.
Face flies feed on nose, eye and wound secretions, and do not feed on blood. They are the cause of ear flapping and head shaking when around cattle. The flies are found anywhere on the cattle’s face, especially nostrils and eyes.
As face flies scrape into the cattle’s eyeballs to get their fluid, they spread pathogens throughout a herd. U-MN says the major economic impact of face flies is the cost associated with treating pink eye.
Cleanliness is important in reducing pasture fly populations, but fly traps such as the Spalding Cow-Vac or a homemade one are an effective way to reduce the number of pasture flies on cattle.
Mix of management
Spray or even other insects can be management tools to keep flies controlled. U-MN Extension says sprays, ear tags, back rubbers, dusters and pour-ons are not effective alone in controlling premise flies. These methods should all be paired with clean facilities and sanitary management.
Ear tags are effective management against face flies, while dust bags and back rubbers are as well if placed low enough. U-MN advises that the active ingredient of the tags should be rotated to minimize
resistance.
Biological management involves using other organisms to manage fly populations, including other insects. Research is not yet conclusive on how significant the suppression is, but predators and parasitoids may help minimize fly populations.
CROWDING IN HEAT: Cattle will crowd together when flies are bothering them, making fly control essential to prevent further heat stress during hot summer days, according to North Dakota State University.
Producers might find chickens or other birds helpful in fly management through their consumption of fly larvae in pastures or barns.
Parasitoid wasps lay eggs inside of fly pupae, which kills the pupae and prevents flies from hatching. Most effective in confined areas, these wasps may even be available for purchase under the names “fly parasites” or “fly predators.”
No matter what type of flies you have bugging your cattle, take a note from these tips to keep cattle fly-free this season.
Try triple control tactic
University of Minnesota offers up three ways to manage flies in cattle herds:
Keep it clean. Sanitation practices are most important to manage stable and houseflies, which breed in decaying organic materials.
Use chemicals as needed. Products such as ear tags, sprays, back rubbers, dusters and pour-on insecticides work best for face and horn fly management.
Try biological options. While many biological methods of control do not have conclusive research on their benefits, predators and parasitoids may minimize fly populations when paired with sanitization and chemical management.
University of Minnesota Extension contributed to this article.
