Nepidae

[6][7] Exceptionally they have also been recorded from hypersaline lakes and brackish lagoons,[6] the Australian genus Goondnomdanepa is restricted to flowing waters,[7] and Nepa anophthalma is adapted to life in caves in Romania.

[12][3] To keep their orientation in the water they have three pairs of “static sense organs”, small oval structures closely associated with the fourth, fifth, and sixth abdominal spiracles.

The eggs, which are laid above the waterline in mud, decomposing vegetation, the stems of plants or rotting wood, are supplied with air by filamentous processes which vary in number among the genera.

[17] Araripenepa from the Early Cretaceous (Aptian) Crato Formation of Brazil is the oldest known member of the family, and is the sister group to remaining genera.

[18] Authority: Douglas & Scott, 1865 (sometimes called "water stick insects") Genera in this subfamily include: Austronepa and Goondnomdanepa are restricted to Australia.

Nepa cinerea with open forewings , revealing its usually hidden hindwings and red abdomen [ 9 ]
Nepidae have a tail-like siphon or breathing tube, which in some species like this Laccotrephes can be even longer than the body [ 9 ]
With about 100 species, Ranatra is the most diverse genus [ 10 ]