Insects of Britain and Ireland: the families of Hemiptera

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L. Watson and M. J. Dallwitz


Water-scorpion and Water Stick-insect.

Salient features of adults. Foraging under water.

Predacious (on arthropods, tadpoles and small fish). Large; 18–22 mm long (Nepa cineria), or 30–35 mm long (Ranatra linearis); fliers; swimming and moving under water the right way up; relatively stout bodied (Nepa cineria), or with narrow-elongate bodies (Ranatra linearis); conspicuously stilt-legged (Ranatra linearis), or not stilt-legged (Nepa cineria). Rostrum clearly separated ventrally from the prosternum by a sclerotized gula. Antennae inserted underneath the head and much shorter than it, generally invisible from above; non-aristate. Ocelli absent. Fore-wings well developed; in the resting insect lying more or less flat over the abdomen; differentiated into a basally thickened and a distally membranous region; with a clavus. Fore-legs modified and raptorial. The abdomen terminating in a long, bristle-like respiratory siphon (this comprising two filaments, which may become detached as in the illustration).

With conspicuously modified, raptorial forelegs, and the abdomen terminating in an elongated respiratory siphon.

Taxonomy. Suborder Heteroptera; Notonectoidea.

British representation. 2 species in Britain; genera 2. Nepa, Ranatra. E.g., Ranatra linearis (Linear Water-scorpion).

Illustrations. • Ranatra linearis (Linear Water-scorpion: B. Ent. 281). • Ranatra linearis (dissections: B. Ent. 281). • Ranatra linearis (legend+text: B. Ent. 281). • Ranatra linearis (text: B. Ent. 281, cont.). • Nepa cinerea (Water Scorpion: B. Ent. 700). • Nepa cinerea (Water Scorpion: B. Ent. 700, legend+text). • Nepa cinerea (Water Scorpion: B. Ent. 700, text cont.). • Ranatra linearis (Shaw and Nodder, about 1802). • 'The Great Surinam Nepa' (Exotic species, Shaw and Nodder, about 1798). • Nepa, Ranatra and other aquatic bugs (Southwood & Leston). • Ranatra linearis, with Corixidae, Notonecta and Plea: Saunders (1892).. • Nepa cinerea, with Miridae, Aphelocheirus and Ilyocoris: Saunders, 1892..

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the families of Hemiptera. Version: 16th May 2016.’.