Abstract: The succession and its mechanism of cotton pests in Xinjiang were summarized in this paper.From 1950s to 1960s,the main pests were yellow cutworm (Agrotis segetum),tarnished plant bug (Lygus pratensis),tobacco thrips (Thrips tabaci),and aphid (Aphis medicaginis);while from 1970s to 1980s,the main pests were cotton bollworm (Heliothis armigera),tobacco thrips (Thrips tabaci),aphid (Acyrthosiphom gossypii),and two-spotted spider mite (Tetranychus urticae);and from 1990s,the main pests were cotton bollworm (Heliothis armigera),cotton aphid (Aphis gossypii),and two-spotted spider mite (Tetranychus urticae).The main reason for this succession might be the changes in crops distribution,cultivation type,planting method,management technique and over-use of chemical pesticides and fertilizers.

Key words: Form, Rapeseed, Toxicity