一、梨圆介的危害情况林业局苗圃梨园16.6公顷,1991年定植,主栽品种香梨。梨圆介最初出现在1995年,1996年零星发生,主要危害树枝干和果实,造成树皮开裂,枝条枯折。在果实上早期呈米粒大小浅红斑,后期脱落后为凹陷绿点,品质下降。由于管理措施不当,导致了1998年梨圆介壳虫大发生,园中的树全部染上介壳虫,相当一部分树1/3的枝干被介壳虫致密覆盖,采摘的香梨95%以上有介壳虫,商品率几乎为零。二、梨圆介的生物学特性梨圆介属同翅目盾介科,在我区每年发生三代,1～2龄若虫附着在枝条上越冬。第二年春天树液 First, the harm of Pear Circle mediated Forestry Bureau Nursery Liyuan 16.6 hectares, planted in 1991, the main varieties fragrant pear. Pear circle mediated initially appeared in 1995, sporadic occurrences in 1996, the main damage to the branches and fruits, resulting in bark cracking, branches dilapidated. In the early fruit was rice size light erythema, late fall green dots after depression, the quality of decline. As a result of improper management practices, the pests of Phaeoylocarpus grandiflora occurred in 1998. All the trees in the park were dusted with scale insects. A considerable part of the 1/3 branch of the tree was densely covered by scale insects. More than 95% Insects, commodity rate is almost zero. Second, the biological characteristics of Pear Circle mediated Pear Circle mediated Homoptera Shield Medaka, occurs in our district three generations each year, 1 to 2 instar nymphs attached to the branches of the winter. The second year spring sap