棉田夜蛾有甘蓝夜蛾、斜纹夜蛾、甜菜夜蛾三类，初孵幼虫群集叶背取食叶肉，３龄后可将叶片吃成孔洞或缺刻，４龄后分散为害。甘蓝夜蛾和甜菜夜蛾幼虫主要取食叶片；斜纹夜蛾幼虫取食叶、花蕾和果，严重时可将全田作物吃光。甘蓝夜蛾一年发生２～３代，发育适宜温度为１８... Cotton bollworm have cabbage Lantern, Spodoptera litura, beet armyworm three kinds of newly hatched larvae cluster leaves back to take leaf meat, after 3 years can be eaten into a hole or notch leaves, scattered after 4 years of age. The cabbage beetles and beet armyworm larvae mainly feed on the leaves; the Spodoptera lutea larvae feed on the leaves, buds and fruit, and the whole crop can be eaten in severe cases. Brassica campestris occurs 2 to 3 generations a year, the development of suitable temperature is 18 ...