Larval hemocytes of the greater wax moth, Galleria mellonella L. 1758 (Lepidoptera: Pyralidae), were classified by fluorescence microscopy staining with acridine orange. Based on their fluorescence characteristics, plasmatocytes and prohemocytes could be easily distinguished from granulocytes because they appear faint green and do not contain any fluorescent granules in their cytoplasm. Nuclei of granulocytes emit bright green fluorescence when observed under fluorescence microscope. Prohemocytes are round and their nuclei are bright. Plasmatocytes are irregularly shaped. Therefore, all three types of the wax moth's major hemocytes that are difficult to identify by bright field or phase contrast microscopy can be easily classified by fluorescence microscopy with staining acridine orange. Furthermore, this technique will assist further studies to understand how hemocyte differentiation and regeneration proceeds in larval hematopoietic organs and during hemocyte transformation. The fluorescent method for hemocyte classification is more precise than the common method of hemocyte identification using bright field or phase contrast microscopy.