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松黑叶蜂主要为害油松和华山松幼林。1963—1964年,该虫在陕西黃龙山林区大量发生,为害严重,轻者针叶被食残缺不全,逐渐枯黄;重者针叶食光,树木死亡。据发生年份的调查,黄龙山北寺山林场受害的500亩油松幼林,有虫株率均达100%,而且虫口密度和受害程度也逐年俱增。1964年的株平均虫口密度较1963年增加了6.9倍;1964年,因針叶全被取食而致幼树死亡的百分比较1963年增加了4.7%。同时,受害树木的高生长也逐年下降,受害严重较受害轻微的树木高生长,三年中相差80.6厘米,仅1964年一
Pine black bee mainly damage pine and Pinus armandii young forest. From 1963 to 1964, the insects occurred in a large area in Huanglongshan forest area of Shaanxi Province, which caused serious damage. The light ones were eaten incompletely and gradually became yellowish. The heavier needles consumed light and the trees died. According to the survey of the year, the 500-acre young stands of Pinus sylvestris plantation damaged in Beisishan Forest Farm in Huanglong Mountain have a strain rate of 100%, and the population density and degree of insects also increase year by year. The average density of strains in 1964 increased by 6.9 times compared with that in 1963; in 1964, the percentage of young trees that died of feeding on conifers was 4.7% more than in 1963. In the meantime, the high growth of the affected trees also declined year by year, with serious damage being higher than those with slight damage. The difference between the two trees was 80.6 cm in only three years,