Insects of Britain and Ireland: orders
Adult insects. Nearly always found near water. Predatory. Medium sized to very large; capable of flight; with two pairs of propellant wings. Body much elongated, dorsiventrally flattened to laterally flattened. Head hypognathous. Mouthparts well developed; of the biting type; not piercing; more or less conforming to the generalized biting type (but clearly adapted for predation, with wide gape, strongly toothed mandibles, spined maxillae with unsegmented palpi, and labial palpi modified into large lateral lobes, each of the latter equipped near its apex with a moveable hook and a spine or end-hook). Antennae inconspicuous; exhibiting considerable differentiation among the few segments - scape relatively large, pedicel variable, the distal flagellum thin; 3–5 segmented. Ocelli always 3. Wings four; of similar texture in both pairs. Fore-wings membranous. Hind-wings similar in size to the fore-wings; no broader than the fore-wings; not folded in the resting insect. Wings with numerous cross-veins; more or less naked. Wings of the resting insect outspread. Tarsi 3 segmented. Abdomen fairly conspicuously appendaged at the rear; with cerci clearly visible at its tip. Abdomen of females with no exserted ovipositor. Abdomen apparently 10 segmented (all ten complete and flexibly articulated).
Larvae. Larvae aquatic (with tracheal gills); spectacularly predatory (equipped with a large, prehensile, hinged labium for seizing prey, which can include tadpoles and fish); with three pairs of segmented thoracic legs; without ventral abdominal prolegs. Development of larva into adult gradual; exopterygote; not involving a pupal stage.
Classification. Subclass Pterygota; Division Exopterygota.
British representation. 9 families; genera 21; 45 species (described individually in the accompanying data set).
General comments. Hovering and darting hunters, the eyes very large and the abdomen much elongated. The large, hinged labium of the nymphs of Odonata, with the labial palps bearing moveable hooks and constituting pincers, is unique.
Illustrations. • Aeshna cyanea (from Shaw and Nodder, about 1800). See the accompanying data set for illustrations of all the British Odonata. • Libellula depressa (from Shaw and Nodder, about 1800). • Agrion splendens (from Shaw and Nodder, about 1800). • Pyrrhosoma and Ceriagrion? (from Shaw and Nodder, about 1800). • Oxygastra curtisii: B. Ent. 616. • Oxygastra curtisii: B. Ent. 616, legend+text. • Oxygastra curtisii: B. Ent. 616, text cont.. • Leucorrhinia dubia: B. Ent. 712. • Leucorrhinia dubia: B. Ent. 712, legend+text. • Leucorrhinia dubia: B. Ent. 712, text cont.. • Aeshna cyanea emerging from nymph: Shipley 196. • Agrion, adult and nymph (Lubbock 1890).
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: orders. Version: 16th May 2016. delta-intkey.com’.