棉铃虫在我县棉花上常年发生５代，其中一代在棉田外寄主上为害，自二代起迁入棉田为害棉花。１９９８年我县一代棉铃虫发生普遍，且在棉花上造成了一定的为害。据调查，苗床百株卵量一般２～１０粒，最高２０粒，有卵苗床达８０％以上；移栽大田后，百株卵量仍高达２５粒... Cotton bollworm occurs on cotton in our county for five generations all the year round, one generation of which is harmful to the host outside the cotton field. Since the second generation, cotton moved into the cotton field. The generation of cotton bollworm in our county occurred in 1998 and caused some damage on cotton. According to the survey, the seedbed of a hundred eggs generally 2 to 10, up to 20, with more than 80% of the egg bed; transplanted field, the number of eggs is still up to 25 ...