药剂防治稻纵卷叶螟的适期,经我们多年实践的体会,认为以二至三龄时为好。因为: 1.稻纵卷叶螟的发生期不整齐,同一时间内有不同虫态和不同虫龄的幼虫,不可能在短期内连续施药,当早发部分幼虫进入三龄时施药,既可减少药治次数,又可兼杀三龄前后的幼虫,而不致造成损失。 2.各龄幼虫取食量:一龄占总食量的0.63％,二龄占1.1％,三龄占3.9％,四龄占15.3％,五龄占79.1％。三龄以前防治造成损失较小。 Pharmacy control of rice leaf roller the right period, by our many years of practice experience, that the second to third age as well. Because: 1 C. thunbergii Occurrence is not regular, at the same time there are different insect states and larvae of different ages, can not be applied continuously in the short term, when the early part of the larvae into the third instar when the application, Can reduce the number of drug treatment, but also kill the larvae before and after the third age, without causing damage. 2. The larval feeding amount of each instar: The first age accounted for 0.63% of the total food intake, the second was 1.1%, the third was 3.9%, the fourth was 15.3% and the fifth was 79.1%. Prevention and control of the third age caused less damage.