Abstract: 【Aim】 The physiological status of migratory insects is complex， and this influences the stability and accuracy of synthetic sex pheromone lure trapping. This study aims to study the efficacy of sex pheromone lure trapping on monitoring the population dynamics of the rice leaf roller， Cnaphalocrocis medinalis during different migration periods， and the relationship between sex pheromone lure trapping and ovarian development of female adults of this moth. 【Methods】 Synthetic sex pheromone lures and sweeping net were used to monitor the population dynamics of C. medinalis in four localities， i.e.， Ningbo city and Wenzhou city of Zhejiang province， Binyang county of Guangxi autonomous region and Ningdu county of Jiangxi province， from September 2015. The female ovaries were dissected and the features of female ovaries for gradation were photographed. Bivariate correlation analysis was conducted to analyze the relationship between sex pheromone lure trapping and ovarian development of female adults. 【Results】 From late June to mid July， the rice leaf roller in Binyang county was the mixed population of the emigrant and local breeding generations. Various stages of ovaries were found in Binyang county but the proportions of stagesⅠand Ⅱ ovaries were higher than those of other stages. In early July， the rice leaf roller in Ningdu county was the immigrant generation， and most ovaries (>70%) were in stage IV and the proportion of mated adults was 91.3%. Adults were moving out from Beilun district of Ningbo city in late September, and the number of adults reduced gradually till they all disappeared. The ovaries of female adults in Beilun were immature and no mating was found. The adults collected in Ouhai district of Wenzhou city in early October might be the transit generation from Ningbo city， and the number of adults reduced gradually till they all disappeared， too. Stages II and III were the main ovarian stages of C. medinalis in this region. Mating was found in some female adults in Wenzhou， but oviposition was not found. For the immigrant generation， the transit generation and the local breeding generation， the population dynamics monitored with sex pheromone lure trapping was similar to that monitored with sweeping net. Sex pheromone lure did not trap emigrant male adults， because they were sexually immature. However， emigrant adults could be collected by sweeping net. Correlation analysis showed that there was a significant correlation between the number of male adults trapped by sex pheromone lure and the number of adults collected by sweeping net (P<0.05)， and there was also an extremely significant correlation between the number of male adults trapped by sex pheromone lure and the number of sexually mature female adults (P<0.001). 【Conclusion】 Sex pheromone lure can be used for accurate monitoring of the population dynamics of C. medinalis. Due to the extremely significant correlation between the population dynamics monitored with sex pheromone lure and the ovarian developmental stages of female adults， sex pheromone lure trapping might be better than the disturbing and counting method for predicting the population levels and control time of C. medinalis.

Key words: Cnaphalocrocis medinalis, sex pheromone lure, migration, ovarian development, population dynamics