Thomas and Jameson1 state that as a result of the application of ‘Gammexane’ in field trials reductions in wireworm populations of up to 65 per cent have been obtained. Numerous similar trials were laid down by the Cambridge Advisory Centre in the spring of 1946, in conjunction with Imperial Chemical Industries, Ltd. ‘Gammexane’ was applied in powder form at various strengths, to test its efficiency in the control of wireworms on arable crops. In the majority of these trials, which included wheat, oats, barley, sugar beet and reseeded grassland, the plant establishment in treated plots was satisfactory or normal compared with plots receiving no treatment, where it was poor or failed entirely.