Nepidae

Nepidae are found on all continents except Antarctica. They mostly inhabit stagnant or slow-moving freshwater habitats like ponds, marshes, canals and streams. Exceptionally they have also been recorded from hypersaline lakes and brackish lagoons, ==Taxonomy==

Nepidae has around 250 species in 14 genera divided into two subfamilies, Nepinae and Ranatrinae. but the family also includes species-poor genera, like the Ethiopian Borborophilus, Nepella, Nepitella and Paranepa (each with one species), and Australian Austronepa (one species) and Goondnomdanepa (three species). The subfamily Ranatrinae are sometimes called "water stick insects". Genera in this subfamily include: Austronepa and Goondnomdanepa are restricted to Australia. Cercotmetus is from Asia to northern Australia and resembles Ranatra (Worldwide distribution), although the former has a distinctly shorter siphon. Genera ==Appearance and ecology==

Nepidae are brown insects, but some species have a bright red abdomen that can be seen when the wings are open. Their body is broad and flat (subfamily Nepinae) or long and thin (subfamily Ranatrinae). They are rather poor swimmers and typically crawl about on aquatic vegetation. They can fly, but this is infrequently seen. Respiration in the adult is achieved by means of the caudal process, which consists of a pair of half-tubes capable of being locked together to form a siphon. Air is conducted through it to the tracheae at the apex of the abdomen when the tip of the tube is thrust above the surface of the water (similar to a snorkel). In some species the siphon is longer than the body, In immature forms the siphon is often underdeveloped and respiration takes place through six pairs of abdominal spiracles. Their frontal legs are modified into raptorial appendages that are used to grab their prey. They feed primarily on aquatic invertebrates such as other insects, but occasionally take small fish or tadpoles. 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. == Gallery ==

File:Laccotrephes cf brachialis, Pretoria, j.jpg|Nepidae have a tail-like siphon or breathing tube, which in some species like this Laccotrephes can be even longer than the body File:Water scorpion (Nepa cinerea).jpg|Nepa cinerea with open forewings, revealing its usually hidden hindwings and red abdomen ==See also==