晋南棉区,棉铃虫一年发生四代。第一代主要在苜蓿及早春作物上为害,从第二代起开始集中在棉株顶部嫩叶正面产卵。卵量多少,一般与被害程度密切有关,故当百株卵量骤增时,被视为适当防治时机的标志。 Jinnan cotton area, cotton bollworm occurs four generations a year. The first generation mainly in the alfalfa and early spring crop damage, from the second generation began to focus on the front of young cotton leaves spawn positive. The amount of eggs, usually with the degree of victimization is closely related, so when a hundred ovipositive surge, is considered a sign of the appropriate timing of prevention and treatment.