松毛虫是松树的大敌。是我省松林中常发性害虫,主要发生在桥山林区、韩城雷寺庄林区、商州二龙山和安康文武山林区,每隔8～10年大发生一次,每次持续2～3年,从未休止,危害面积少则数万亩,多则40多万亩。大发生时虫口密度千头以上,约有30～60％的针叶被食,局部地区叶被吃光,松林形似火烧,一片枯黄,严重时造成枯死。 Pine caterpillar is the enemy of pine trees. It is a common pest in pine forests in our province. It occurs mainly in Qiaoshan forest area, Leisihuang forest area in Hancheng, Erlongshan in Shangzhou, and Wukongshan forest in Ankang. It occurs once every 8 to 10 years and lasts for 2 to 3 years. Not stop, harm the area of ​​less than tens of thousands of acres, as many as 40 million mu. When the insect population density of more than a thousand or so, about 30 to 60% of the needles were eaten, leaves were eaten in some areas, the pine forest shaped like a fire, a yellow, causing serious death.