The potato tuber moth Phthorimaea operculella is a potato major pest in Egypt. Larvae of P.operculella were inoculated with a granulosis virus (PoGP) showed different cytopathic effects . PoGV induced characteristic symptoms of slow motion, white milky appearance and swilling of the body. Light micrograph of PoGV infected larvae figured out several histological changes. It was found that the midgut epithelial cells were the main targets of the virus infection. Columnar cells, goblet cells and regenerated cells loose their identity and become disorganized, also breaking down of peritrophic membrane and basement membrane and red colour appeared due to presence of granules particles. The morphological structures of P. operculella infected larvae with granulosis virus as well as healthy ones were examined by SEM. It showed complete destruction of external larval body , abdominal segments overlapped in some , prolegs and thoracic legs reduced in size and also the circular shaped spiracles converted to oval shape with rupture and disrupted inside tissue compared to healthy one.