SUMMARYControl of aphids by the four systemic insecticides, dimethoate, disulfoton, menazon and phorate, applied as granules below seed potatoes at planting, was investigated under different soil moisture conditions. Results confirmed previous conclusions that dimethoate and menazon are more effective in wet than in dry soils, whereas disulfoton and phorate are equally effective in both. However, even with dimethoate and menazon effects of moisture were small and were probably the result of several different interacting factors.