Methoprene: Field Tested as a Feed Additive for Control of Face Flies12

Abstract

In 1975, when methoprene was fed to grazing cattle in a block formulation at an average rate of 0.54 mg AI/kg body wt, bioassays and counts of adult flies indicated that populations of Musca autumnalis De Geer were reduced. In 1976, when methoprene was fed to similar cattle in a loose mineral supplement at an average rate of 0.07 or 0.13 mg AI/kg body wt, 45–90% of face fly pupae did not eclose, but counts of adults on the cattle were not reduced markedly. In both years, counts of adult horn flies, Haematobia irritans (L.), were lower on the treated herd than on the check herd.