白蜡绵粉蚧 ( Phenacoccusfraxinus)在西宁市 1年发生 1代 ,2个龄期。 3月中、下旬雌雄若虫分化、结茧化蛹 ,4月上旬开始羽化 ,5月上旬产卵 ,6月中旬开始孵化 ,8月下旬 1龄若虫开始蜕皮 ,1 0月上旬 2龄若虫开始在白蜡树皮裂缝、翘皮下、芽鳞间、树杈、侧枝背阴面结茧越冬。白蜡绵粉蚧在西宁市的城西、城中、城南、城东区的危害率分别为 95 .7%、79.2 %、62 .2 %、3.4%。 Phenacoccusfraxinus Occurs in Xining for 1 Year, 2 Stages. In mid-to-late March, the male and female nymphs differentiated and cocoon pupation, beginning to emerge in early April, spawning in early May and hatching in mid-June. The first instar nymphs started molting in late August and the second instar nymphs started in early October Ash bark cracks, Alice skin, bud scales, tree branches, collateral shade back to the winter cocoon. The damage rates of white powdery mealybugs in urban west, central, southern and eastern districts of Xining City were 95.7%, 79.2%, 62.2% and 3.4% respectively.