河北省第五代棉铃虫发生情况的回顾１９９４年棉铃虫在河北省大发生，虫情前轻后重，逐代加重，特别是第五代棉铃虫大发生，其发生数量之大，危害范围之广，历年罕见。１发生特点①发生范围广，为害作物多。据统计，全省第五代棉铃虫发生面积２４４．１９万公顷。其中棉田... Review of Occurrences of the Fifth-Generation Cotton Bollworm in Hebei Province In 1994, the cotton bollworm occurred in Hebei Province. Before the insects, the light and heavy insect pests became heavier and heavier after generation, especially the fifth generation cotton bollworm. Wide, rare over the years. 1 Occurrence ① Occurrence of a wide range of crop damage. According to statistics, the province’s fifth generation of cotton bollworm area occurred 2441900 hectares. Which cotton fields ...