三代棉铃虫的发生为害期在7月下旬至8月上中旬,其主要特点是:①寄主植物多。除棉花外,还为害玉米、花生、高粱、番茄、辣椒等多种作物。又是雨季,下雨天成虫不出来活动,故产卵持续时间长且部位分散(田间调查时,卵量漏查率一般在30％左右),卵峰不突出,常常出现2～3个较小的卵峰,在大发生的年份又常与四代棉铃虫重叠发生,给防治带来诸多困难;②抗药性 Three generations of cotton bollworm pests in late July to mid August, its main features are: ① host plants and more. In addition to cotton, but also harmful corn, peanuts, sorghum, tomatoes, peppers and other crops. But also the rainy season, the rain does not come out of adult activities, so spawning a long time and scattered parts (field survey, the egg leakage rate is generally about 30%), the egg does not prominent, often 2-3 small Of the egg peak in the year of occurrence of large and often overlap with the fourth generation of cotton bollworm, prevention and control to bring a lot of difficulties; ② resistance