Nepidae is a family of exclusively aquatic Heteropteran insects in the order Hemiptera. They are commonly called water scorpions for their superficial resemblance to scorpions, due to their raptorial forelegs and the presence of a long slender process at the posterior end of the abdomen, resembling a tail. There are 14 genera in the family, in two subfamilies, Nepinae and Ranatrinae. Members of the genus Ranatra, the most widespread and species-rich genus, are sometimes called needle bugs or water stick insects as they are slenderer.
While water scorpions do not sting with their tail (it is used for breathing), they do have a painful bite (strictly speaking a sting by their pointed proboscis), but this is much less harmful to humans than a true scorpion’s sting.
Source: Wikipedia
Subfamily Nepinae
Tribe Nepini
(Singapore)
Subfamily Ranatrinae
(Kaeng Krachan NP, Thailand)