苹果和梨树上的重要害虫各有二、三十种,多数是在树上和果园里过冬的(表1、2)。在果树休眠期防治越冬害虫有很多有利条件:(1)冬季时间较长,北方从10月下旬开始到翌年4月上旬,前后约五个半月;(2)害虫大都集中潜伏越冬,有利于集中消灭;(3)这时果树处在休眠时期,抗药力较强,在生长期不能施用的一些高浓度杀虫剂,如波美5度的石硫合剂和含油量4—5％的矿物油和煤焦油乳 There are two or thirty pests of appalling pests in apples and pears, most of them in winter in trees and orchards (Tables 1 and 2). There are many favorable conditions for controlling overwintering insect pests during dormancy of fruit trees: (1) the winter time is longer, the northern part starts from late October to early April the following year, about five and a half months before and after; (2) (3) At this time, the fruit tree is in dormancy stage, strong antibiotic resistance. Some insecticides with high concentration that can not be applied during the growth phase, such as Baume 5 degrees sulfur and sulfur oil and 4-5% mineral oil And coal tar milk