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在北方所称松毛虫,是指落叶松毛虫、油松毛虫和赤松毛虫,三者常混发生、其危害,落叶松毛虫最重;赤松毛虫最轻;中间是油松毛虫。三者习性大致相同,只是油松毛虫和赤松毛虫比落叶松毛虫要求气候稍温暖些。它们在北方均一年一代,幼虫7—8龄,以3—4龄幼虫在树干基部的土层及枯枝落叶层下越冬。次年4月中下旬日平均气温7—10℃时幼虫上树取食针叶,6月下旬以7龄以上老熟幼虫化蛹,7月中下旬羽化产卵,8—10月份新幼虫为害,10月末幼虫
Dendrolimus in the north, refers to the larch caterpillars, oil pine caterpillars and red caterpillar, the three often occur, the harm, the most important; Dendrolimus caterpillars; Cissus caterpillar the lightest; in the middle of the pine caterpillar. The three habits are about the same, but the oil pine caterpillars and Dendrolimus caterpillar need more slightly warmer climate. They are uniform in the north for generations, with larvae 7-8 years old, with 3-4 instar larvae wintering over the soil layers and litter at the base of the tree trunk. The average temperature in mid and late April was 7-10 ℃, the larvae fed on the tree needles, in late June to mature larvae over the age of 7 pupation, oviposition in mid-and late July spawning, 8-October new larvae damage The end of October larvae