The pear psyllid, Cacopsylla pyricola (Foerster) Hemiptera: Psyllidae) was recorded for the first time on pear trees, Pyrus communis L. in some pear orchards in north Sinai and Ismailiya Governorates (Ahmed, 2007). Damages caused to pear trees due to infestation with the pest were described throughout morphological and histological changes in artificially infested potted pear seedlings. The morphological changes occurred on the leaf and stem. The histological changes in the tissues of leaf, stem and roots were also described from transverse sections. The abnormal growth in the infested pear seedlings may be due to the salivary toxin secretions excreted by the insect during feeding process. The honeydew secretions secreted by different stages of the pear psyllid during feeding process stimulate the growth of sooty mould. The histological changes due to infestation by C. pyricola showed distinct reduction, particularly plant height as well as the photosynthesis was greatly affected as a result of crumpling leaves and growth of the sooty mould on them.