Insects of Britain and Ireland: orders

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L. Watson and M. J. Dallwitz



Adult insects. Terrestrial (mostly), or aquatic (not uncommonly, in either the adult or the larval stage, or both: see the accompanying data set); nearly always found near water (some genera), or not particularly associated with water. Predatory, or phytophagous, or imbibing nectar, or saprophagous, or coprophagous, or consuming stored produce, or mycophagous (with a few leptinids and staphylinids ectoparasitic on mammals known outside Britain); conspicuous ‘jumpers’ (a few), or not ‘jumpers’; voluntarily emitting sound (not uncommonly, by stridulation), or mute. Minute to very large; with hardened ‘elytra’ (q.v.), representing the fore-wings (nearly always), or without elytra (rarely, e.g. in female Drilidae and Lampyridae); capable of flight (nearly always), or flightless (in a few forms); usually with one pair of propellant wings (the hind pair). Body dorsiventrally flattened, or more or less cylindrical, or laterally flattened. Head prognathous to hypognathous; prolonged into a rigid beak (with the mouthparts at its tip), or not rigidly beaked (in most families). Mouthparts well developed; of the biting type; not piercing, or piercing (or probing: notably in the very numerous forms constituting the Weevils (Curculionoidea), where the head is produced forwards to form a rostrum which bears them at its tip); more or less conforming to the generalized biting type (mostly adapted for biting, but the usual strong mandibles vary from being hugely emphasized, as in Lucanidae, to being much reduced, as in Scarabaeinae. The curculionid rostrum is widely employed by the females in boring holes to receive their eggs, but details of its function in males and relation to adult feeding habits are elusive). Antennae conspicuous, or inconspicuous; variously complex, or simple; (2–)7–11(–20) segmented. Compound eyes present and well developed (nearly always), or vestigial or absent (in specialized cavernicolous species, and inhabitants of other dark places, e.g. Leptinus). Ocelli 0, or 1, or 2. Wings two, or four (usually, but the elytra and/or the hind-wings are sometimes absent or much reduced); the single pair when only one pair, leathery, or horny; typically markedly differently textured in the two pairs (the fore-wings represented by the hardened ‘elytra’). Fore-wings (elytra) horny (usually), or leathery. Hind-wings similar in size to the fore-wings, or larger than the fore-wings; markedly broader than the fore-wings, or no broader than the fore-wings; folded in repose. Wings with few cross-veins; conspicuously hairy, or more or less naked; fringed (the hind-wings, sometimes), or not fringed. Wings of the resting insect closed and directed backwards. Tarsi (3–)5 segmented. Abdomen conspicuously appendaged at the rear, or not conspicuously appendaged (mostly); exhibiting a conspicuous ovipositor, or not spectacularly appendaged; lacking clearly visible cerci. Abdomen of females with an exserted ovipositor, or with no exserted ovipositor. Abdomen apparently 8 segmented, or 9 segmented (9 being modified as the genital segment and hidden within the body, and 10 being greatly reduced).

Larvae. Larvae terrestrial, or aquatic; feeding in the open (especially when predatory), or clandestine feeders (generally, when non-predatory); predatory (including forms living in the nests of bees and other Hymenoptera), or phytophagous, or saprophagous, or coprophagous, or consuming stored produce, or mycophagous; with three pairs of segmented thoracic legs, or without segmented thoracic legs (in which case, distinguishable from most other legless insect larvae in combining a fully sclerotized head capsule with a body that is crescent-shaped and thicker in the middle); nearly always without ventral abdominal prolegs; without anal prolegs. 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; without articulated mandibles; with free appendages (usually), or with the appendages fused to the body (rarely).

Classification. Subclass Pterygota; Division Endopterygota.

British representation. 95 families, described individually in the accompanying data set; genera about 1000; about 3700 species.

Special features. The wingless adults of female Lampyridae and Drilidae larviform, with the thorax clearly segmented.

Illustrations. • Representing Coleoptera. For numerous images of Coleoptera, see the ‘Families of British Coleoptera’ data set. • Carabus violaceus (Violet Ground-beetle: B. Ent. 446). • Adults (left) and larvae (right: Lubbock 1890). Scolytus. Curculio. Meloe. Apalus. Acilius.

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.’.