RESUMEN
We characterized individual morphological types of the rose sawfly, Arge ochropus (Gmelin) (Hymenoptera: Argidae), hemocytes for the first time by means of light and differential interference contrast microscopy and scanning and transmission electron microscopy. Four types of hemocytes were identified in the hemolymph of larvae and pupae of A. ochropus: prohemocytes, plasmatocytes, granulocytes, and oenocytoids. Prohemocytes are the smallest type of hemocytes, rounded to ovoid cells with large nuclei. Plasmatocytes are polymorphic and variable in size. Granulocytes are oval and spherical cells variable in size, with variable number of rough endoplasmic reticulum, mitochondria, and microtubules in the cytoplasm. Oenocytoids contain eccentric nucleus and cytoplasm with small mitochondria and few rough endoplasmic reticula. Differential hemocyte counts indicated that plasmatocytes are the most abundant hemocyte type during early instars while granulocytes are the most abundant hemocyte type in the last instar. The pattern of total hemocyte count changed during rose sawfly development and reached its peak in prepupae and then declined slowly in the pupal stage.