1.Distribution Cosmopolitan pests,distributed in Asia, Europe and North America; >Sitodiplosis mosellana favors warm environment.Mainly occur in wheat growing areas of valleys of Yellow River and Huai River in 31-35 N.in China. >Contarinia tritici prefers cool environment. Mainly distributed in wheat growing areas of alp and altiplano. ¾ Cosmopolitan pests, distributed in Asia, Europe and North America; ¾ Sitodiplosis mosellana favors warm environment. Mainly occur in wheat growing areas of valleys of Yellow River and Huai River in 31-35°N. in China. ¾ Contarinia Contarinia tritici tritici prefers cool environment prefers cool . Mainly distributed in wheat growing areas Mainly distributed in wheat growing areas of alp and of alp and altiplano altiplano. 1. Distribution 1. Distribution