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辽源市地处吉林省东南部,属于半山丘陵地区,有林地面积近一百五十万市亩。其中人工落叶松林为八十万市亩左右。一九六四年以来,落叶松毛虫[Dendrolimus superans(Butler)]曾连续大发生,至一九六八年全市林区发生面积达二十五万市亩,严重的林分有虫株率达70％。虫口密度高达106条/株,平均为46条/株。使树木不能正常生长,从而为次期性害虫(如小蠹虫、天牛等)的侵入和大量繁殖提供了有利条件,造成林木的枯死或降低利用价值。
Liaoyuan City, located in southeastern Jilin Province, belongs to the Mid-Levels Hilly region, with a forest area of nearly 1.5 million mu. The artificial larch forest is about 800,000 mu. Since 1964, Dendrolimus superans (Butler) has occurred continuously. By 1968, an area of 250,000 mu in the forest area of the city occurred. 70%. Insect population density up to 106 / strain, an average of 46 / strain. So that the trees can not grow normally, thus providing favorable conditions for the invasion and multiplication of the secondary pests (such as beetles, celastrus, etc.), causing the trees to die or reducing the utilization value.