Water scorpion, Laccotrephes maculates Fabr. is unisexual and exhibits sexual dimorphism. The males are relatively smaller with conspicuous commexival spines and posses’ distinct external genitalia. The male reproductive organs include a pair of testes, a pair of vasa deferentia, a pair of vesicula seminalis, two pairs of accessory glands and unpaired median ductus ejaculatorious. The female reproductive organs possess a pair of ovaries, a pair of lateral oviducts, a common oviductus communis, a vagina and he spermatotheca. Water scorpion, Laccotrephes maculatus Fabr. possesses a pair of salivary reservoirs (SR) associated one, with each main salivary gland (MSG). Each salivary reservoir is a white, elongated sac like structure at the posterior end of which is produced into a narrow-closed tubule. The intimal cuticular lining of the reservoir is very thin. The reservoir often collapses on being empty due to the extreme thickness of its inner lining. The epithelial layer of the reservoir does not show any secretory activity which suggests that it is concerned with the storage of the saliva only. The epithelial layer of the reservoir, close to its junction with the duct consists of tall columnar cells, with distinctly visible nuclei.