The red palm weevil, Rhynchophorus ferrugineus Olivier is a widely distributed serious pest of the young coconut and date palms and hence occupies an important status in the field of economic entomology. This book deals with the cytological studies of haemocyte identification and classification; The circulating haemocytes in the haemolymph of R. ferrugineus is identified and classified based on light microscopic and electron microscopic studies. In all the different stages studied, the haemocyte complex comprises prohaemocytes, plasmatocytes, granulocytes, adipohaemocytes, oenocytoids and spherulocytes. Prohaemocytes are small, round cells with large nucleus. Plasmatocytes are large fusiform cells with granular cytoplasm. Granulocytes are spherical, oval or irregular cells with granular cytoplasm. Adipohaemocytes are spherical or oval cells with refringent lipid droplets in the cytoplasm. Oenocytoids are generally large, oval or spherical cells with several kinds of inclusions in the cytoplasm. Spherulocytes are oval or round cells with compact nucleus.