The effects of juvenile hormone analogue pyriproxyfen on total hemocyte count and hemocyte morphology of Galleria mellonella pupae were investigated. Pyriproxyfen was applied to last instar larvae of G. mellonella topically on the dorsal thorax. Five hemocyte types; prohemocytes, plasmotocyte, granulocyte, spherule cells and oenocytoids were identified in pupae hemolymph based on morphological criteria. A significant decrease was observed in total hemocyte count exposed to 1,5 and 10 mu g/ml of pyriproxyfen. Pyriproxyfen treatment caused different levels of deformations on almost all hemocyte types. Vacuolization in granulocytes, loss of pseudopod in plasmatocytes becoming round shaped, rarefaction in cytoplasm, forcing nucleus through the cell membrane were identified. Mitotic division and some cells lost their smooth cell boundary to become irregular were also determined as a result of toxic effects of pyriproxyfen.