一、发生概况和发生趋势籼型杂交水稻自从七十年代中期在全国各地推广以来,稻螟不断地发生变化。七十年代后期至1985年以前,长江中下游各稻区,三化螟种群数量逐年下降,不少地区无需开展三化螟的药剂防治工作;而二化螟种群数量则在迅速上升。特别是湖南、江西、浙江、湖北和四川等省的大部分地区,二化螟的发生量和为害程度超历史记录,并且由以前主要为害早、中 First, the occurrence of the situation and trends Indica hybrid rice since the mid-seventies in all parts of the country since the promotion, the rice borer constantly changing. From the late seventies to the year 1985, the populations of rice stem borer and rice stem borer in the middle and lower reaches of the Yangtze River decreased year by year. In many areas, it is unnecessary to carry out chemical control of the rice stem borer (Chilo suppressalis); however, the population of Chilo suppressalis is rapidly rising. Especially in Hunan, Jiangxi, Zhejiang, Hubei and Sichuan provinces most of the area, the occurrence and degree of damage of Chilo suppressalis over historical records, and by the previous major damage early, middle