玉米螟在江苏如皋地区一年发生3代,有的年份有不完全4代。一代为害玉米,二代为害玉米和棉花,三代集中为害棉花。常年各代产卵高峰期分别为5月底6月初、7月中旬、8月中旬。一、二代期距约45天,二、三代约一个月。玉米螟在棉田产卵有98.98%产于叶片反面,而又以下部叶片卵量最大,下部1—5果枝卵量占67.35%,6 Corn borer occurred in Rugao, Jiangsu Province, three generations a year, some years are not completely 4 generations. A generation of harmful corn, the second generation of corn and cotton damage, focus on the three generations of cotton damage. Perennial generations of spawning peaks were the end of May early June, mid July, mid August. One or two generations from about 45 days, two or three generations of about a month. Corn borer oviposition in the cotton field was 98.98% produced on the opposite side of the leaves, while the lower part of the leaves the largest amount of eggs, the lower part of 1-5 fruiting eggs accounted for 67.35%, 6