近年来,一代二化螟在四稻(双季早稻、早中稻中稻、双晚)混栽区和一季稻区发生危害逐年加重。在四稻混栽区,随着双季早稻的减少,越冬代二化螟成虫的产卵对象主要集中在中稻秧田和早栽中稻大田,因而中稻上危害面积也逐年增大,我区发生危害面积已由1987年的1.086万亩上升到1991年的6.4万亩,分别古本地10万亩中稻的10.86％和64％;田间枯心率由1987年的1.5～5.26％上升到1991年的5.3～11％,高的达29.9％,给中稻生产带来很大威胁。在指导防治上,原来提出在卵孵盛期后3～5天或5～7天用药一次,若防效差,7天后可再用药一次,其效果往往 In recent years, one generation of stem borer in the four rice (double early rice, early middle rice, double late) mixed planting area and a quarter of the rice crop hazards have increased year by year. In the four-rice mixed planting area, with the reduction of double-season early rice, the spawning objects of the adult rice borer were mainly concentrated in middle-season rice seedlings and early-planted middle-aged rice fields, thus the area harmed on mid-season rice also increased year by year, The area has risen from 1.086 million mu in 1987 to 64,000 mu in 1991, accounting for 10.86% and 64% respectively of the 100,000 mu of middle-aged paddy in ancient times. The dry heart rate has risen from 1.5 to 5.26% in 1987 to 5.3 ~ 11%, up 29.9%, to bring a great threat to the production of rice. In the guidance of prevention and control, the original proposed in the egg hatch after the period of 3 to 5 days or 5 to 7 days medication once, if the poor control, 7 days after the re-use of drugs, the effect is often