稻纵卷叶螟是水稻的主要害虫之一。怎样做好“两查两定”,正确定好防治指标和防治田块,对消灭虫害,确保水稻丰收,有着重要的意义。过去对纵卷叶螟的危害有“叶子白一白,产量减一百”的说法。因此,把稻纵卷叶螟的防治指标定为:苗期每亩幼虫密度6,000条或百丛稻有新虫苞30个;穗期每亩幼虫密度4,000—5,000条或百丛稻有新虫苞15—20个,定为防治对象田。从近几年来的综合防治试验、示范的实践中看出,这个防治指标似乎低了一些,特别是早、晚稻品种有早、中、晚熟类型,其防 Rice leaf roller is one of the main pests of rice. How to do a good job of “two check and two fixes”, correctly set control targets and prevention and control of plots, is of great significance to eliminating pests and ensuring the harvest of rice. In the past the dangers of leaf roller borer “white leaves white, yield minus one hundred” argument. Therefore, the prevention and control of the Cnaphalocrocis medinalis as: seedling density of 6,000 per acre larvae or a hundred clusters of rice new wormy 30; per acre larvae at the heading of 4,000-5,000 or new pests 15-20 buds, as the control object field. From the comprehensive prevention and control experiments and demonstration practice in recent years, it can be seen that the index of prevention and control seems to be lower. In particular, the varieties of early and late rice have early, middle and late maturity types,