通过田间调查和人工接种，首次发现梨九绵蚜是在梨树根部为害的重要新害虫，并确定梨九绵蚜营异寄主全周期生活，其原生寄主为榆，次生寄主为梨。５ 月中旬至 ６ 月初，梨九绵蚜以有翅干雌成蚜迁飞到梨园，在梨树根梢产无翅孤雌侨蚜为害；１０ 月初至 １１ 月初，又以有翅性母成蚜迁飞到榆树上产雌、雄性蚜，交配后雌蚜产卵，以卵越冬；春季干母、无翅干雌、有翅干雌为害榆叶形成伪虫瘿。 Through field investigation and artificial inoculation, it was first found that Pear was the most important pest in the root of pear and identified the perennial life of the host. The primary host was Ulmus and the secondary host was Pear. From mid-May to early June, pear aphid flew into the orchards with winged dry aphids to pear orchards. In the early to early November and early November, Aphids migrate to elm to produce female and male aphids, female aphids after mating spawn, the eggs overwinter; spring dry mother, wingless stem female, winged stems and leaves of female Yishu form pseudo insects.