1College of Life Science，Northeast Agricultural University，Harbin 150030，Heilongjiang，China|2Institute of Vegetables and Flowers，Chinese Academy of Agricultural Sciences，Beijing 100081，China
Abstract：The dynamics of western flower thrips（WFT）〔Frankliniella occidentalis（Pergande）〕and its natural enemies on plastic shed cultivation vegetables were investigated during spring and autumn seasons in Beijing．The results showed that the population grew slowly on sweet pepper planted in spring season during 30 days after transplanting. But the pest number increased rapidly with the emergence of flowering period and remained at a high level in June．The number of WFT in autumn season sweet pepper was obviously lower than that in spring．The pest preferred to feed in flowers．The observed natural enemies of WFT were ladybirds，lacewings and flower bugs，and the flower bug（Orius spp.）was the dominant insect，which had some control effect to WFT．
