Abstract: By using yellow sticky traps, an investigation was made on the population density of adult Sitodiplosis mosellana in vertical direction and the sex ratio of the adults in a wheat field. The activities of the adult S. mosellana in the wheat field were mainly at 0-40 cm  above the ground, and the population density decreased with increasing height. The sex ratio of the adults varied widely in different eclosion periods, with a higher percentage of males in the early period but nearly 100% of females in the late period. In vertical direction, the percentage of the females increased with increasing height. Weather factors played an important role in the dispersal of adult S. mosellana.  

Key words: flue-cured tobacco, climate change, suitability.