Producer Question from 2013
Q. What are the best fly control options for cattle on summer pasture? (May 3, 2013)
For current information, please see the "Fly Control for Cattle on Pasture in Nebraska" (May 2016) article.
A. There are three major pasture fly species present in Nebraska that are bothersome to cattle: horn fly, face fly, and stable fly.
Horn Fly Control
There are many methods available to reduce horn fly populations on cattle — sprays, dusts, backrubbers (self-oilers), insecticide ear tags, pour-ons and insect growth regulators (oral larvicides and feed-throughs). Efficacy, cost, convenience, and herd management practices should be considered when implementing a horn fly control program.
Insecticide ear tags are one of the most convenient methods of horn fly control. There are several ear tags which have provided good control of horn fly numbers though the fly season. Application of insecticide ear tags should be delayed until late May or early June to insure season-long horn fly control. Care must be taken when choosing the correct ear tag due to wide-spread resistance (pyrethroids) — rotate ear tags annually.
Sprays and pour-ons provide approximately 21 days of control so re-application will be required through the fly season.
Back rubbers and dust bags are effective ways to apply insecticides, but they can be less convenient since they both require re-charging. Back rubbers and dust bags work the best where cattle are forced to use them.
Insect growth regulators (oral larvicids and feed-throughs) work by disrupting the growth of fly larvae. For this method to be successful cattle must consume the product daily and neighboring cattle herds located nearby must be under some type of fly control as horn flies have the ability to migrate several miles per day.
Face Fly Control
Reducing face fly numbers can be difficult since the female face fly spends very little time on the animal. Options for face fly control include whole animal sprays, dust bags, back rubbers, insecticide ear tags and insect growth regulators (oral larvicides and feed-throughs).
Insecticide-impregnated ear tags provide reasonable good face fly control. Face flies are equally attracted to adult animals and calves. So calves need to be tagged as well as adult animals. Pyrethroid tags provide the best reduction in face fly numbers, but can enhance horn fly resistance. To reduce horn fly resistance, rotate insecticide ear tags annually.
Insect growth regulators which will reduce face fly numbers are rabon, phenothiazine, and diflubenzuron. Methoprene (altosid) is not registered for face fly control.
If face fly numbers are extremely high, control may require more than one method of treatment.
Stable Fly Control
Stable fly populations on pastured cattle are extremely difficult to control due to the behavior of the fly. Stable flies feed mainly on the animal's legs and for a short period of time. Dust bags, oilers (back rubbers), pour-ons and insecticide ear tags are relatively ineffective in providing effective control. Feed additives are ineffective because stable flies develop in decaying organic material not fresh cattle manure. Whole animal sprays and mist blower applied applications will reduce stable fly numbers, but these treatments need to be applied at least every 14 days.
Recent research has indicated that cleaning up winter feeding sites of hay in and around round-bale feeders can help reduce stable fly numbers. Also, these areas can be treated with an insect growth regulator, Neporex® which can help reduce stable fly larval development.
Of course, always read and follow label directions when using a pesticide!
For additional information regarding pasture flies and their control methods, please contact your local extension office or Dave Boxler, UNL Extension Educator.
Dave Boxler
West Central Research and Extension Center
University of Nebraska–Lincoln
308-696-6721
dboxler1@unl.edu