Methoprene for Control of the Horn Fly: a Sustained-Release Bolus Formulation for Cattle12

Abstract

A sustained release bolus containing 1% methoprene inhibited the development of Haematobia irritans (L.) in the manure of treated cattle for an average 10–12 weeks. A 40-g bolus with a specific gravity of ca. 2.1 was retained in the reticulum of cattle. Erosion of the bolus, apparently the principal mechanism of release of the methoprene, decreased from ca. 0.4 g/day after 10 days in the animal to ca. 0.2 g/day at 90 days.