Insects of Britain and Ireland: orders

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L. Watson and M. J. Dallwitz



Adult insects. Predatory, or phytophagous, or saprophagous (Panorpa feeds on small arthropods, but perhaps only when these are incapacitated, while Boreus is unusual in this generally carnivorous Order in feeding on vegetable matter). Small to medium sized; capable of flight, or flightless (the wings rudimentary and without venation in the Boreidae, being represented by two pairs of slender, bristle-like vestiges in tbe males and a single pair of scale-like lobes on the mesothorax in the females); when wings fully developed, with one pair of propellant wings, or with two pairs of propellant wings. Body more or less cylindrical. Head hypognathous; prolonged into a rigid beak (via the extended clypeus). Mouthparts well developed; of the biting type; piercing, or not piercing (?); more or less conforming to the generalized biting type (but with the clypeus and labrum elongated to form a rostrum bearing the other components). Antennae conspicuous; simple; 15–35 segmented (‘many-segmented’). Ocelli 3. Wings two (i.e., in the females of Boreidae), or four; when two pairs are present, of similar texture in both pairs (and commonly conspicuously maculated). Fore-wings membranous. Hind-wings when two pairs are present, 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 (sometimes slightly hairy, but not conspicuously so). Wings of the resting insect closed and directed backwards; not held roof-like. Tarsi 5 segmented. Abdomen conspicuously appendaged at the rear (male Panorpa, with the ninth sternum prolonged into two styliform arms, its tergum prolonged into a subquadrate plate, and a pair of laterally inserted, two-segmented claspers between the dorsal and ventral processes thus formed), or not conspicuously appendaged; with cerci clearly visible at its tip (these short, two-segmented or ostensibly three-segmented via narrow basal prolongations); apparently 11 segmented (tergum 1 fused with the metathorax, but the sternite free).

Larvae. Larvae feeding in the open; predatory (?), or phytophagous, or saprophagous; caterpillar-like, with three pairs of segmented thoracic legs; with ventral abdominal prolegs (on segments 1–8: Panorpidae), or without ventral abdominal prolegs (Boreidae); with paired anal prolegs (at least, the abdominal apex often modified into a suction disc: Panorpidae), or without anal prolegs (Boreidae). The abdominal prolegs when present, without crochets. Larval head with a well sclerotized capsule. Development of larva into adult involving marked metamorphosis; endopterygote; involving a pupal stage.

Pupae. Pupae without a puparium; with articulated mandibles; with free appendages.

Classification. Subclass Pterygota; Division Endopterygota.

British representation. Boreidae, Panorpidae; genera 2 (Boreus and Panorpa); 4 species.

General comments. The vernacular name ‘Scorpion-fly’ derives from the posture of male Panorpidae, which carry the tip of the abdomen curved upwards and forward.

Illustrations. • Boreus hyemalis (Winter Scorpion-fly: B. Ent. 118). • Boreus hyemalis (dissection details: B. Ent. 118). • Boreus hyemalis: B. Ent. 118, legend+text. • Boreus hyemalis: B. Ent. 118, text cont.. • Panorpa germanica: B. Ent. 696. • Panorpa germanica: B. Ent. 696, legend+text. • Panorpa germanica: B. Ent. 696, legend cont.. • Panorpa communis, with dissections.

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.’.