The present study showed that mucous cells in the gills of damselfly larvae were found mainly in the surface of the gill lamellae when employing with Schiff’s reagent (PAS test), and recognized the presence of muco-polsaccharides. The present cells of the epithelium of the caudal gills have been found to contain acid muco-polysaccharide. The perusal of literature pertaining to the histochemical investigation of the different zones of the caudal gills of Zygopteran Odonate larvae revealed that practically no work has been done so far on these taxa. The aim of the present work was to study histochemical characterization of the caudal gills of damselfly larvae to investigate the deposition of chemicals in respiratory epithelium of the caudal gills of Zygopteran larvae.