A natural family of water scorpions.

Nepidae is a family of insects in the order Hemiptera, suborder Heteroptera. Sometimes it is placed in the infraorder Nepomorpha.http://tolweb.org/tree?group=Nepomorpha They are commonly called water scorpions for their superficial resemblance to a scorpion, which is due to the modification of the legs of the anterior pair for prehension, and to the presence of a long slender process, simulating a tail, at the posterior end of the abdomen. There are two genera in the family, Nepa and Ranatra.