Evaluation of a synthetic pyrethroid for tabanid control on horses and cattle

An emulsifiable concentrate and a dust formulation of the synthetic pyrethroid permethrin (which has proved effective in the laboratory and in the field against tabanids [see preceding abstract]) were evaluated on horses, ponies and calves in Texas against Tabanus subsimilis Bellardi, T. sulcifrons Macq. and T. proximus Wlk. Emulsion sprays containing 0.05 or 0.1% active ingredient applied to calves at rates of 1 litre/animal resulted in 90% mortality of flies exposed to the animals 9 and 14 days after treatment, respectively; these same dosages applied to horses and ponies gave 90% mortality 12 and 18 days after treatment. Dust formulations containing 0.025% toxicant were less effective on both cattle and horses, but dust formulations containing 0.25% toxicant gave 90% kill of flies exposed to treated cattle and horses 10 and 12 days, respectively, after treatment.