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杨干象是杨树幼树的一种毁灭性蛀干害虫,在辽宁一年发生一代,以初龄幼虫和少量卵在枝干叶痕的木栓层中越冬。4月上旬,当日平均温度增至8～10℃时,越冬幼虫普遍活动,4月中下旬大部分发育至二龄。一二龄幼虫在木栓层和韧皮部内为害,被害处首先在树皮上出现针头大小的小孔,稍后排除棕褐色的丝状粪,再后树皮呈水渍状,蛀食坑道呈不规则片状,因此时树木的水分和养分刚刚开始流动,如能及时杀死幼虫,对杨树尚不能造成太大危害。到4月末、5月上旬,当平均温度达到12℃以上
Yang dry elephant is a destructive stem borer of young poplar trees, occurring in Liaoning a generation a year, with the first instar larvae and a small amount of eggs in the branches of leaf cork plywood wintering. In early April, the average daily temperature increased to 8 ~ 10 ℃, the overwintering larvae generally active in mid-to late April most of the development to the second age. One or two instar larvae in the cork layer and phloem damage, the victim first appeared in the bark of needle-sized holes, later ruled out brown silk manure, and then the bark was water-like, tunneling was Irregular flaky, so when the trees just began to flow of water and nutrients, if they can kill larvae, the poplar can not cause too much harm. To the end of April, early May, when the average temperature reached 12 ℃ above