Abstract: 【Aim】 The meadow moth, Loxostege sticticalis L., exhibits intermittent population dynamics. This study aims to reveal the causes for the termination of the 2nd and 3rd outbreak periods of L. sticticalis in China. 【Methods】 We analyzed the migration dynamics of L. sticticalis in 1983 and 2009 using trajectory analysis, explored the climatic background of population fluctuation by calculating anomalies of temperature and precipitation and checking the atmospheric circulation background responsible for abnormal climatic condition. 【Results】 In June of 1983, extremely low temperature and excessive precipitation occurred in Northeast China and East Siberia of Russia, and severe drought occurred in North China, resulting in a large-scale population collapse event of L. sticticalis with the overwintering area being limited within the high-altitude area in northern Shanxi province in autumn of 1983. The parasitism rate of natural enemies in northern Shanxi province reached a rather high level in spring of 1984, further suppressing the population of L. sticticalis, and leading to the termination of the 2nd outbreak period. In June of 2009, Northeast Asia experienced extremely bad climate similar to that in June of 1983, and then a largescale population collapse event of L. sticticalis occurred again in Northeast China, North China, and East Siberia and Far East of Russia, resulting in the termination of the 3rd outbreak period. Abnormal atmospheric circulation pattern was the direct cause of these two extreme climate events. 【Conclusion】 Extreme climate event has become an important factor causing the termination of outbreak periods of L. sticticalis in China. Due to large uncertainty of extreme climate event, long-term prediction for the termination of outbreak periods of the meadow moth in China is difficult to be made in the current stage.

Key words: Loxostege sticticalis, outbreak period, population collapse, extreme climate event, migration