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Two years of field trials in Nigeria with the synthetic pyrethroids permethrin, cypermethrin and decamethrin against Glossina palpalis (R.-D.) and G. tachinoides Westw. are described. Laboratory tests were also made against G. morsitans submorsitans Newst. The three pyrethroids were applied successfully from the ground at 0-5%, 0-3% and 0-075 %, respectively, to fly resting sites on vegetation using pressurised knapsack sprayers, populations of both species being eradicated after a single application of one insecticide. Following residual spraying from a helicopter, only decamethrin at 30 g/ha achieved complete eradication. It was thought that, with permethrin wettable powder at 200 g/ha, by modifying the spraying equipment and, with cypermethrin, by increasing the dosage to over 150 g/ha, both could be successful in the future. A new ' sideways' spraying technique tested using the helicopter gave promising results. Comparatively little harm was done to non-target organisms in the environment after spraying with any of the three pyrethroids, and it is expected that they may gradually replace the chlorinated hydrocarbons in future routine anti-tsetse operations.

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