一、梨圆蚧壳虫的发生与为害 梨圆蚧壳虫在梨树上一年发生2代,在苹果树上一年发生3代,多数以1龄或2龄若虫在树枝和树干上越冬。少数以受精雌成虫越冬。梨圆蚧壳虫主要发生在梨、苹果、杏、枣等果树上,以若虫和雌成虫固着在寄生枝、干、叶的背面以及叶柄和果实表面刺吸汁液。枝条受害后衰弱,发芽既弱又晚;梨果受害的果面上发生黑褐色斑点,致使梨果个儿小、变硬,甚至果面龟裂,不能食用; Pear Scale Pest Occurrence and Pests Pest Scale pests Occur in the pears two generations a year, occurred in the apple tree three generations a year, most of the first instar or second instar nymphs in the branches and trunk of the winter . Few female adults to fertilize wintering. Pest insects Occurred mainly in pears, apples, apricots, jujube and other fruit trees, with nymphs and female adults fixed in the parasitic branches, stems and leaves on the back and petiole and fruit surface sucking juice. After the branches damaged weak, sprouting both weak and late; pear fruit damage on the surface dark brown spots, resulting in a small pear fruit, hardened, and even fruit cracking, can not eat;