Shoo, Fly: Fly Management of Pasture Cattle

Posted: April 23, 2018 | Written By: Kristi L. Allwardt, M.S., Form-A-Feed Nutritionist

fly management

Fly Management

Cattlemen are well-aware that as the seasons change, so must their management strategies. Mitigating threats within the herd is essential to maintaining profitability and performance of the operation.  External parasites can significantly affect performance and herd health, which in turn has the potential to decrease profitability.  An important focus during this time of year is the emergence of the fly population and its impact on summer grazing beef cattle. While there are three fly species that can economically influence beef cattle production, the most crucial for pasture management is the horn fly (Haematobia irritans).

Horn Flies

Horn flies are small in size (approximately half the size of a House fly) and are often found on the back and sides of cattle. Eggs are laid in fresh manure and within 18 hours a new population of horn flies will emerge. Development from egg to a sexually mature fly takes 10 to 14 days. They are an aggressive, biting pest that feeds on the blood of the animal; typically averaging 20-30 blood meals per day.  These painful bites and constant presence cause irritation to cattle which results in a defensive behavior. Switching of tails, restlessness, twitching of sides and kicking at their bellies are indications that cattle are experiencing distress from the fly population. Research has indicated that the economic threshold for the horn fly population is 200 flies/animal. Once exceeding this limit, more energy is spent on the animal defending itself rather than being productive in the herd. Decreased milk production and reduced daily gains due to horn flies have been well documented, as well as significant reduction in calf weaning weights. The annual economic impact the horn fly has on North American cattle production is estimated to be $1 billion. For comparison, bovine respiratory disease is estimated between $800 to $900 million, annual loss.

Control Methods

Monitoring horn fly numbers through routine observations can best determine the appropriate management decisions needed for the herd. An effective horn fly management program will be contingent on efficacy of the product, convenience, and cost.  There are a wide range of products and methods available for the producer to implement, depending on what is most suitable for the operation.

Forced-use dust bags/oilers: Self-treatment dust bags or oilers are an effective method for horn fly control. These must be hung in areas that “force” the animal to walk under them. For example, high traffic areas which are ideal for forced-use methods include; alleyways, between pastures, and near water or feed sources. This is an economical choice that provides little to no stress on the animal.

Pour-ons: Ready-to-use insecticides that can be applied on the back of cattle. Efficacy range is dependent on available options, but will likely need re-application throughout the season. Use of this method is effective but requires animal handling.

Animal sprays: Effective way of reducing fly numbers on the animal but typically last 2 to 3 weeks before re-application is needed. This method can be time consuming and may not be suitable for some producers’ grazing situations.

Insecticide ear tags: This practice has been around for many years and is still commonly used. Many tags require two tags/adult animal and one tag/calf for optimum control. Tags should wait to be applied until the horn fly threshold has been met. Follow label directions for best -use practices. This method is easy to apply and proven effective, but requires additional animal handling.

Feed additives: Oral larvicide that is typically supplemented as a loose mineral, tub or block for cattle on pasture. The insect growth regulator passes through to the manure to kill developing fly larvae. Cattle must consume a designated amount of the product daily. This method decreases the emergence of new larvae population but may have little effect on adult flies if nearby herds are left untreated.

The Form-A-Feed Solution

Speak with your Form-A-Feed Representative about a horn fly management and resistance plan. A combination of select methods can provide the best defense for your herd; overall protecting profitability and performance of the animal. In an effort to provide producers with an economical feed-through option, Form-A-Feed has developed a vitamin-mineral supplement which contains the insect growth regulator S-Methoprene for the control of horn flies.

Power Pro Encompass-W with Altosid® is not only an effective fly control method, but also contains highly bio-available trace minerals, vitamin fortification and yeast to stimulate rumen function and intake.

Contact us today to learn more about this product and how Form-A-Feed can help your operation thrive!