Livestock Entomology

2014 Horn Fly Data


The 2014 Horn Fly data was compiled from two different 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.


- Stillwater Overall

- Valliant Overall



To see the current list of insecticidal 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



The Stillwater location had a total of seven treatments. Five groups were treated with insecticidal impregnated ear tags, one used the VetGunĀ® system, and the last was an untreated control group.




The VetGunĀ® group was retreated after populations were surveyed on WAT6 and WAT12.




The Valliant location had five treatments. Four were treated with insecticidal impregnated ear tags, and the last was an untreated control group.



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