Abstract: . Experiments were carried out during 1990-1991 in the greenhouses and two typical types of plastic tunnels for vegetable production in Daqing, Helongjiang Province on the control of the aphid Myzus persicae by inundative releases of mass reared aphid midge, Aphidoletes aphidimyza. Releasing the predator at a predator:prey ratio of 1:20 when the aphid population reached 200 aphids/plant in the greenhouse and the small sized tunnel reduced the aphid populations by 75.1-91.8% and 80.1-90.5%, respectively, 9-12 days after the release. In 1990, a single release was made in 5 large sized tunnels, respectively, at the predator:prey ratio of 1:20. The aphid population reduction was 82.2% 10 days after the release. The aphid population was suppressed below 141.2-150.5 aphids/plant for 30 days. During June-July, 1991, releases were made on pepper in 16 large sized tunnels at same ratio but in 2-3 releases during two weeks period, with 86.4% reduction of the aphid population 10 days after the last release. The aphid populations continued to decline and were effectively suppressed for 60 days till removal of the first planting crcp, during which period, no additional insecticide application was needed.