Insects of Britain and Ireland: orders

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L. Watson and M. J. Dallwitz

Lepidoptera

Moths and Butterflies.

Adult insects. Not particularly associated with water (the majority), or nearly always found near water (when the larvae feed on helophytic or occasionally aquatic plants). Imbibing nectar, or incapable of feeding; voluntarily emitting sound (only Acherontia, which squeaks like a mouse by forcing air through the proboscis), or mute (the rest). Small to very large; capable of flight, or flightless (notably in the females of some genera); usually with two pairs of propellant wings. Body dorsiventrally flattened to laterally flattened. Head hypognathous. Mouthparts well developed (mostly), or much reduced (some groups being characterised by the haustellum and palpi being lacking or vestigial); functional for feeding (mostly), or non-functional for feeding (when the haustellum is lacking or non-functional); suctorial (mostly), or of the biting type (in Eriocraniidae and Micropterigidae, which alone have functional mandibles and a hypopharynx specialized for grinding pollen); not piercing; conforming to the generalized biting type to highly modified (mandibles absent or vestigial save in the Micropterigidae and Eriocranidae, and the maxillae usually greatly modified, with their galeae much elongated, internally grooved and fastened together by interlocking hooks and spines to form the tubular proboscis (haustellum) through which food is drawn). Antennae conspicuous, or inconspicuous; simple, or complex; 15–35 segmented (i.e., “many-segmented”). Ocelli 0, or 2. Wings when present, i.e. usually, four; of similar texture in both pairs to markedly differently textured in the two pairs (the fore-wings often firmer). Fore-wings membranous. Hind-wings smaller than the fore-wings to larger than the fore-wings; markedly broader than the fore-wings, or no broader than the fore-wings; folded in repose, or not folded in the resting insect (in butterflies, in particular). Wings with few cross-veins; conspicuously scaly (the covering being more or less complete, except in Sesiidae and a few Sphingidae where the scales are restricted to the bodies and legs and to coloured areas of the largely clear wings); without ‘corneous dots’ (differing in this respect from those of Trichoptera); fringed. Wings of the resting insect held above the body, with their upper surfaces more or less apposed, or outspread, or closed and directed backwards; when closed and directed backwards, held roof-like over the abdomen, or not held roof-like. Thoracic legs present. The body and legs of wingless adults bearing scales (comparable with those on winged forms). Tarsi 5 segmented. Abdomen conspicuously appendaged at the rear, or not conspicuously appendaged; exhibiting a conspicuous ovipositor, or not spectacularly appendaged; lacking clearly visible cerci (cerci entirely lacking). Abdomen of females with an exserted ovipositor, or with no exserted ovipositor (mostly). Abdomen apparently 6–9(–10) segmented (the sternum of 1 being lacking, and 7–10 often involved in the structures of the genitalia).

Larvae. Larvae terrestrial (mostly), or aquatic (Pyralidae-Nymphulinae); feeding in the open (mostly), or clandestine feeders (in folded leaves, leaf miners, wood and stem borers); phytophagous (mostly), or saprophagous, or consuming stored produce, or mycophagous; with three pairs of segmented thoracic legs; with ventral abdominal prolegs (nearly always), or without ventral abdominal prolegs (in some leaf mining forms); with paired anal prolegs (usually), or without anal prolegs (in some leaf mining forms). The abdominal prolegs bearing crochets. Larvae brightly coloured (often, when exposed feeders, and often conspicuously hairy or bristly), or drab. 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 (rarely, e.g. Zeugloptera), or without articulated mandibles (almost invariably); with free appendages (only in a few supposedly primitive forms, e.g. Eriocranidae), or with the appendages fused to the body (nearly always).

Classification. Subclass Pterygota; Division Endopterygota.

British representation. 61 families, described individually in the accompanying data set; genera about 670; about 2200 species.

Special features. The wingless adults not larviform, with only obscure thoracic segmentation.

General comments. The fringed wings are characteristically covered on both surfaces with broad, overlapping but easily removable, coloured, stalked scales. The body and legs are also densely scaly, including wingless females and those forms in which the wings are mainly bare of them.

Illustrations. • Representative Lepidoptera: Noctuidae (Humphreys). The British Noctuidae are comprehensively illustrated from Curtis, Newman, Kirby and other classic works, in the ‘Genera of Noctuidae’ data set. • Melanic and light forms of Lepidoptera-Noctuidae from N. Staffs, 1950s. • Representative Lepidoptera: Geometridae (Humphreys). The British Geometridae are comprehensively illustrated from Curtis, Newman, Kirby and other classic works, in the ‘Genera of Geometridae’ data set. • Representative Lepidoptera: Geometridae (Kirby). • Melanic and light forms of Lepidoptera-Geometridae from N. Staffs., 1950s. • Representative Lepidoptera: Pyraloidea (Kirby). • Representative ‘microlepidoptera’ (Kirby). Representatives from all the Families of British ‘microlepidoptera’ are illustrated from Curtis, Kirby and other classic works, in the ‘Families of British Lepidoptera’ data set. • Representative lepidopteran: Papilionidae (Shaw and Nodder, about 1802). Parnassius apollo. All the British butterflies, along with representatives of all the Families of British Lepidoptera, are illustrated in the ‘Families of British Lepidoptera’ data set.


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’.

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