Livestock Entomology

2015 Horn Fly Data

The 2015 Horn Fly data was compiled from multiple locations. Each location had its own set of treatments. The treatments used were chosen from the commercial horn fly control products that were available at that time.



To see the current list of horn fly control products click here.


information to know before you buy ear tags

The following is information over horn fly insecticide resistance management and how to properly rotate tags each year.


  • Begin horn fly control procedures in the spring when cattle average approximately 200 horn flies.
  • If ear tags are used, the insecticide classes must be rotated. Do not use a pyrethroid ear tag more than once every three years. Do not use an organophosphate ear tag more than two years in succession. Continuous use of ear tags in the same insecticide class will eventually result in horn fly resistance.
  • Remove ear tags at the end of the fly season or when they lose their effectiveness. Do not tag cattle more than once per fly season, regardless of insecticide class.
  • If additional horn fly control is needed later in the year, use sprays, pour-ons, dusts or backrubbers. If possible, alternate insecticide classes when changing control methods.
  • If pyrethroid ear tags have failed to control horn flies in the previous year, pyrethroid insecticides in any form should not be used for at least two years. In the meantime, use non-pyrethroid ear tags, sprays, pour-ons, etc.
  • Pyrethroid Tags should be used NO more than once every three years
  • Organophosphate Tags should not use more than two years in a row
  • What animals should receive tags?

YES: Heifers, Cows and Weaned Calves

NO :  Bulls and Calves still on their mother


Alfalfa County

The Alfalfa County location was set up based on a strong influence from the producers in the area. The local producers had questions on the differences in application techniques for horn fly control. The Livestock Entomology Lab joined with the local county extension agent, the Northwest Area Livestock Specialist and volunteer producers for this trial.

The Alfalfa County location had multiple treatments based on what the producers already deployed for horn fly control as well as techniques they wanted to observe. The treatments are outlined below.

-Treatment 1 -  XP820® ear tags with Western® Stress Aid 6 Mineral C-4000 with fly control

-Treatment 2 - XP820® ear tags

-Treatment 3 - Monthly rotation of Ultra Saber® pour-on and Ultra Boss® pour-on

-Treatment 4 - XP820® ear tags

-Treatment 5 - Monthly rotation of Ultra Boss® pour-on and Prolate/Lintox HD® spray

-Treatment 6 - Monthly application of Prolate/Lintox HD® spray

-Treatment 7 - Monthly application of StandGaurd® pour-on

-No Treatment - Control



This trial outlined not only how the chosen products worked in comparison to others but also the importance of chemical class rotation, applying the insecticide correctly and the benefit of IGR implementation.

 The cattle groups were sampled to get the initial populations in April then treated within the following week. Then the cattle were sampled on a monthly basis. The groups requiring monthly treatment were sampled the day before re-treatment to show the effects the insecticides had after a month had passed.

If there are any questions regarding this trial, please contact us.


The Stillwater location had a total of seven treatments. Three groups were treated with insecticidal impregnated ear tags, one with an insecticidal spray, one with an insecticidal pour-on, one used the VetGun® system, and the last was an untreated control group.



The spray, pour-on and VetGun® group were retreated every 4-5 weeks depending on horn fly populations. WAT 14 is what the populations reflected four weeks post re-treatment in August of 2015.

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