The effects of cypermethrin on the hemocytes of pupal endoparasitoid Pimpla turionellae (Hymenoptera: Ichneumonidae) feeding on its host Galleria mellonella (Lepidoptera: Pyralidae) was evaluated after treatment of the host larvae with different sub-lethal doses of the insecticide. Four hemocyte types; prohemocytes, plasmatocytes, granulocytes, and adipohemocytes were identified in parasitoid last instars hemolymph, based on morphological criteria. Dose-dependent changes in the frequencies of mitosis, apoptosis, and micronuclei in hemocytes were determined and compared. Cypermethrin exposure reduced the mitotic activity yet increased the apoptosis in a dose-dependent manner. Mean frequencies per dose in the hemocytes decreased from 27 to 1% and increased from 22 to 113% for mitosis and apoptosis, respectively. Micronucleated cells were rare but their frequency increased in a dose-dependent manner. The decrease in mitosis along with the rapid increase in apoptosis in wasp hemocytes suggests that parasitoids may consume more energy and their defense mechanism may be destroyed due to the depletion in the hemocyte number.