Three field trials with endosulfan against coffee berry borer, Hypothenemus hampei (Ferr.), on both Coffea arabica and C. canephora are described. The insecticide was applied from motorized knapsack sprayers at 20 gal. per acre of an emulsified solution containing 0.2 per cent, active ingredient to the branches bearing the crop.

In two trials endosulfan applied twice at 21-day intervals significantly reduced the numbers of cherries containing living borers and the percentage of damaged cherries at the first pick. In the third trial a single application of endosulfan proved to be as effective as the double one. Increases in yield could not be detected. It was shown, by allowing insects to emerge from caged samples of cherries taken when picking began, that endosulfan did not affect the host/parasite ratio of either H. hampei or Geratitis coffeae (Bez.), nor did it increase the numbers of berry-boring caterpillars.

No off-flavours following treatment could be detected in liquoring trials of robusta coffee beans that were dry processed or pulped and washed.

Laboratory experiments in which adults of H. hampei were exposed above, but out of contact with, filter papers that had been dipped in an emulsified solution containing 0·2 per cent, endosulfan showed that it was acting at least as a partial fumigant and was more effective at 30°C. than at room temperature (21°C); spraying should thus preferably be carried out on warm, sunny days. In view of these findings, and as it is relatively non-toxic, endosulfan is recommended for control of H. hampei in Uganda when heavy attacks occur.