Abstract
Four pour-on formulations, Poron 20(R) (20% phosmet), Somonil(R) (8% methidathion), Ridlice(R) (50% chlorpyrifos) and Lypor20(R) (20% temephos), were tested for efficacy against long-nosed sucking lice (Linognathus vituli) of cattle. Chlorpyrifos and temephos were the most effective but no insecticide eradicated the lice within the 6-week trial period.