Abstract
The massive immigration of rice planthoppers was forecasted based on the numerical weather prediction charts for wind and equivalent potential temperature at 850 hPa (850 hPa chart) provided by the Japan Meteorological Agency during the wet season in Japan. There was a good correlation between the occurrence of warm moist strong winds and immigration of rice planthoppers. An analysis of the 850 hPa chart could efficiently forecast rice planthopper immigrations into Kyushu in the wet seasons from 1996 to 1998. It was, therefore, concluded that this chart is more useful than the low-level jet stream data for investigating migration of rice planthoppers, because it gives not only information of wind but also temperature and humidity.