On today’s Cow-Calf Corner, Dana Zook, Oklahoma State University Cooperative Extension NW Area Livestock Specialist talks about horn fly control.
Spring is my favorite time of year and I have really enjoyed what seems like an extended season this year. Insects will also take advantage of an early spring. One such insect that impacts on beef production is the horn fly. Horn flies increase stress in beef cattle due to their painful bite. Elevated stress reduces milk production, efficiency, and rate of weight gain. A 2017 collaborative research study between Kansas State and Oklahoma State Universities determined stocker cattle with an insecticidal ear tag gained 0.21 more pounds per day compared to their counterparts with no horn fly control. This weight gain resulted in a $12 net profit over the cost of the ear tag during a 90-day summer grazing period (Yin, 2021).
How do you identify horn flies? Horn flies are a small black fly that feeds on the back, sides and belly of cattle and are the most common fly in beef cattle. During the summer months, a generation of horn flies can complete their life cycle in as little as 14 days. Economic losses begin to occur when fly populations reach 150-200 insects per animal. Without means of control, horn fly populations commonly exceed 300 flies/animal.
What are the options of control? Very simple control methods such as dust bags or back rubber/oilers can be utilized but placement of these systems is crucial so that every animal makes direct contact with the fly control agent. If cattle are accustomed to gathering for a feed truck, spraying is a good option. Pour-on products are also popular, but cattle will need to be moved through a chute or alley monthly for accurate product application. Depending on the brand, sprays and pour-on’s will provide 7-21 days of control and will need to be repeated throughout the season. Rainfall events can reduce the duration of effectiveness for spray and pour-on products. Each product varies in terms of application rate and number of applications within a season, so as always, be sure to read and follow label instructions.
Ear tags are another proven horn fly control method. For some producers, application of ear tags may coordinate well with timing of spring vaccination and castration measures. Most fly tag labels suggest 4-5 months of efficacy; however, Oklahoma researchers have found that the chemical of most ear tags is effective in our state for approximately 90 days. Tubs and feed products containing an insect growth regulator (IGR) are also a convenient option to control horn flies. This product is effective because horn flies naturally utilize fresh manure piles to lay their eggs and IGR’s work in the manure to prevent fly larvae from maturing to adult flies. These products should be in place in early spring. Local OSU demonstrations found that these products may work best when used in tandem with other horn fly control methods.
Rotation is important with all horn fly controls due to the potential development of resistance. Due to the short lifespan of horn flies (as little 14 days) many generations of flies are produced in one season, potentially allowing chemical resistance to develop quickly. To avoid this, rotate products from different chemical classes each year. Keep in mind, that just because a product has a different name doesn’t necessarily mean it contains chemicals from different chemical classes. Seek out your OSU extension educator this spring to determine what fly control product is right for you.
References:
Yin, M. (2021). Essays on Horn Fly Control Economics in Stocker Cattle, Stocker Cattle Producer Purchasing Preferences, and Food Insecurity during Covid-19. Doctoral dissertation, Oklahoma State University. https://hdl.handle.net/11244/337099
