4.Life Cycle 1)Brown planthopper 冬 Migratory pest,no diapause. 水 Northern boundary limit is about 12'C isotherm (230-26 N.)in January. *1-12 generations annually in different paddy planting areas;12 in southern Hainan;1~2 just north of 35 N.1) Brown 1) Brown planthopper planthopper ™ Migratory pest, no Migratory pest, no diapause diapause. ™ Northern boundary limit is about 12 Northern boundary limit is about 12℃ isotherm (23 isotherm (23o-26o N.) in January. N.) in January. ™ 1-12 generations annually in different 12 generations annually in different paddy planting areas; 12 in southern paddy planting areas; 12 in southern Hainan; l~2 just north of 35 Hainan; l~2 just north of 35o N. 4. Life Cycle 4. Life Cycle