Field trials to assess the efficacy of permethrin for the control of flies on cattle.

Permethrin [3-phenoxybenzyl (+/-) cis, trans--2,2dimethyl-3-(2,2-dichlorovinyl) cyclopropane-1-carboxylate], a new synthetic pyrethroid, was applied to cattle on farms in the United Kingdom to assess its efficacy in fly control under field conditions. When 250 ml 0.1 per cent permethrin was applied to the backs of cattle using a knapsack sprayer, adequate control of horn flies, Haematobia irritans, was achieved for over three weeks. Application of 500 ml 0.1 per cent all over each animal gave one to two weeks' control of stable flies, Stomoxys calcitrans, and satisfactory control of non-biting flies for one week. Application of permethrin through a spray arch, using approximately one litre 0.05 per cent permethrin for each animal, gave similar control.