Farmers control horn flies based on the husbandry and production practice of their region.
During last summer, the efficacy of the three methods fell appreciably. Dips gave good fix control for about fifteen days, but now they protect animals for much shorter periods ranging from zero to six days. Resistance is also reflected in in vitro assays when horn flies are exposed to filter papers impregnated with fenvalerate. Lethal doses of fenvalerate for horn flies in some areas have increased significantly. Details of these toxicological studies are reported in a manuscript submitted to the Journal of Medical Entomology.