The effects of high voltage electromagnetic fields (EMF) on populations of aphpids, leaf miners and snails associated with rapeseed under subtropical conditions were studied. A field study was conducted during the spring season of 2015, at Wuhan, China (30.59°N, 114.30°E; 23.3 m asl). Plots with four different emission rates (0 kV, 5.2 kV, 26 kV and 39 kV) were established, each containing an EMF emission device located 2.6 m above the soil, Lipaphis erysimi aphid and Liriomyza brassicae leaf miner population densities were recorded at 10 d intervals throughout the cropping season. Aphids, leaf miners and snails infested all plots, but significantly higher population densities of all pests were observed in control plots. The plots with the highest emission rate (39 kV) had lower population densities of pests throughout the entire experiment. High voltage EMF may have the ability to suppress pests of rapeseed. However, much remains to be learned about the suitability and reliability of EMF for insect suppression.