The efficacy of various insecticides which were effective in the laboratory against Otiorhynchus singularis was evaluated in field studies on red raspberry in Scotland in 1984-85. Adults of the curculionid were controlled effectively by 2 sprays of azinphos-methyl plus demeton-S-methylsulphon at 280 g a.i. or of fenitrothion at 550 ml a.i./ha applied at an interval of 7 days. Spraying at night, when the adults were feeding on the plants and exposed to direct spray cover, was more effective than spraying during the day. The reduction in numbers was similar to that given by DDT at 1000 ml a.i./ha, the standard insecticide, which is no longer permitted for commercial use in Europe. HCH at 125 ml a.i./ha and the synthetic pyrethroid insecticides cypermethrin at 50 ml a.i. and deltamethrin at 22.5 and 15 ml a.i./ha were less effective.