Resistance developed rapidly due to widespread tagging using a single chemical family, the pyrethroids, against entire adult populations of horn flies. Continuous exposure to a single class of insecticides rapidly selects for flies with innate tolerance to the insecticide, eventually leading to the failure of the insecticide to provide satisfactory control. Resistance management has become an important issue for producers and can be achieved by altering application methods from one season to the next, and alternating compounds from different chemical classes such as organophosphate and pyrethroid insecticides. Ear tags should be managed to low concentrations of the insecticide that may favor development of resistance. Information on products currently licensed for use in Canada for the control of horn flies is updated and maintained by the Western Committee on Livestock Pests Table of Contents References Colwell, D. D., T. J. Lysyk, A. Whiting, and H. Philip.
Horn fly resistance widespread.
LRC Weekly Letter No. 3056. Floate, K. D. 1997. Off-target effects of ivermectin on insects and on dung degradation in southern Alberta, Canada. Haufe, W. O. 1982. Kunz, S. E., and C. D. Schmidt.