Insects of Britain and Ireland: the families of Lepidoptera

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L. Watson and M. J. Dallwitz


Adults diurnal to nocturnal; relatively short-bodied, or medium-bodied, or long-bodied (often hugely so); mostly heavily built (wingspan less than 8 times the thoracic width); wings in repose spread flat with their lower surfaces more or less appressed to the substrate, or packed with the forewings directed backwards to cover hindwings and abdomen.

Antennae very short to of medium length; extending to about 0.28–0.55 times the length of the forewing; not clubbed. Antennae of males bipectinate. Eyes partly or wholly hairy. Ocelli absent. Chaetosemata absent. Maxillary palps absent. Labial palps porrect; 3 segmented. Proboscis absent.

Wingspan 30–88 mm; 7–9.8 times the thoracic width. Forewings broad; 1.5–2.2 times as long as wide. The outer and hind margins angled at 100–105 degrees. The outer margin slightly sigmoid-curved, or convexly curved (mostly); forewings apically rather pointed, or blunt. Hindwings broadly rounded; similar in breadth to the forewings; with a rounded apex; the upper surfaces conspicuously patterned above, or plain; with transverse lines, or with a discal spot and with transverse lines (but the discal spot usually lacking), or with neither discal spot nor transverse lines; without a frenulum.

Neuration of forewings and hindwings dissimilar. Forewings 12 veined (mostly), or 13 veined; with 1 anal vein (mostly), or with 2 anal veins. The anal veins of the forewings representing 1b only (usually?), or comprising 1b and 1c (Le Cerf and Herbulot illustrating G. quercifolia with 1c vestigial proximally, but long-tubular to the margin). Forewings exhibiting a tubular vein 1c, or lacking a tubular vein 1c (e.g., G. quercifolia). Vein 1b of the forewings simple. The transverse vein complete to incomplete. Discal cell of the forewings without a tubular media (M) vein. Hindwings 9 veined; with 2 anal veins. The anal veins of the hindwings comprising 1a and 1b. Hindwings exhibiting vein 1a; lacking a tubular vein 1c. Vein 1b of the hindwings simple. The transverse vein complete, or incomplete. Hindwings with a praecostal spur (commonly), or without a praecostal spur. 6 veins arising from the hindwing cell. The cell-derived hindwing veins 4+5 proximally joined and 6+7 proximally joined, or 3+4 proximally joined and 7+8 proximally joined. Vein 8 of the hindwings completely independent of the cell, or joined to the cell only by a bar, or anastomosing with the upper margin of the cell; not approximating to vein 7. Often with one or more pseudoneuria from vein 8 of the hindwing.

Fore-legs with a tibial epiphysis (males), or without a tibial epiphysis (females). Tibiae of middle legs 2-spurred. Posterior tibiae 2-spurred (very short); hairy.

Tympanal organs absent.

Eggs, larvae and pupae. Eggs markedly flattened; smooth or minutely pitted. Larval prolegs 10. Larvae conspicuously, densely long-hairy; commonly with urticating hairs (Malocosoma being notorious). On divers dicot trees, shrubs and herbs, plus one on Gramineae.

Pupae concealed (in a cocoon); on the surface of the ground, or above the ground. Empty pupae not becoming protruded.

British representation. Genera 10 (one adventive); 11 species (one adventive). Eriogaster lanestris (Small Eggar), Gastropacha quercifolia (Lappet), Lasiocampa trifolii (Grass Eggar), Lasiocampa quercus (Oak Eggar), Macrothylacia rubi (Fox Moth), Malacosoma castrensis (Ground Lackey), Malacosoma neustria (Lackey), Phyllodesmia ilicifolia Small Lappet), Philudoria potatoria (Drinker), Poecilocampa populi (December Moth), Trichiura crataegi (Pale Oak Eggar). Doubtfully British specimens illustrated by Curtis represent Dendrolimus pini (Pine Lappet), and “Lasiocampa medicaginis” Ochsenheimer (‘Medick Eggar’: probably = Lasiocampa trifolii). Curtis’s 1827 description and illustrations of a male adult and of a larva of the latter do not conform well with L. trifolii. His depiction of the larva, however, was copied from an earlier one by Esper, which was used by Ochsenheimer in preparing the original description.

Classification. Macromoths. Suborder Ditrysia. Superfamily Bombycoidea.

Illustrations. • Lasiocampidae (1): Newman. • Lasiocampidae (2): Newman. • Poecilocampa, Malacosoma, Eriogaster, Lasiocampa, Philudoria, Gastropacha (1): Kirby 27 (part) and 28 (part). • Lasiocampa, Macrothylacia, Gastropacha, Dendrolimus, Trichiura, Malacosoma (2): Kirby 27 (part) and 29 (part). • Malacosoma castrensis (Ground Lackey: B. Ent. 229). • Malacosoma castrensis (dissections: B. Ent. 229). • Malacosoma castrensis: B. Ent. 229, legend+text. • Malacosoma castrensis: B. Ent. 229, text cont.. • Dendrolimus pini (Pine Lappet: B. Ent. 7). • Dendrolimus pini: B. Ent. 7, legend+text. • Dendrolimus pini: B. Ent. 7, text cont.. • Gastropacha quercifolia (Lappet: B. Ent. 24). • Gastropacha quercifolia: B. Ent. 24, legend+text. • Gastropacha quercifolia: B. Ent. 24, text cont.. • Gastropacha quercifolia: neuration. • “Lasiocampa medicaginis” (‘Medick Eggar’, probably = L. trifolii: B. Ent. 181). • neuration: Macrothylocia, Malacosoma. • Lasiocampa, Poecilocampa, Trichiura (Humphreys). • Eriogaster, Euthrix, Lymantria and Malacosoma (Humphreys). • Larvae, cocoon, pupa: Euthrix potatoria, Macrothylacia rubi (Duponchel, 1849). • Larva and pupa: Gastropacha quercifolia (Duponchel, 1849). • Larvae and cocoons: Lasiocampa quercus, Lasiocampa trifolii (Duponchel, 1849). • Larvae, eggs, cocoon, pupa: Malacosoma castrensis, Malacosoma neustria (Duponchel, 1849).

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 Lepidoptera. Version: 8th June 2016.’.