The small brown rice planthopper is an injuriousinsect on food crop of Ningxia.
灰飞虱是宁夏粮食作物上的一大害虫。
2
Clanis bilineata tsingtauica is a kind of argricultral injuriousinsect, distributing in the west and north of china.
豆天蛾是一种大型的农业害虫，在我国西部和北部地区广泛分布。
3
The prerequisite for the natural enemies to be able to control insect pest is that the increase of injurious insects is restrained by the density of the latter.