Insects of Britain and Ireland: the genera of Lepidoptera-Geometridae
Amphidasis, Amphidasys, Eubyja, Pachys.
Adults. Nocturnal; relatively stout-bodied. Antennae of males strongly bipectinate; bipectinate to the apex, or apically simple. Face rough (hairy or rough-scaled). Tongue fully developed, or absent.
Wingspan 45–62 mm. Forewings relatively narrow-elongate. The outer margin of the forewing convexly curved to more or less straight. Forewings whitish, strigulated brown and black, with a brown band after the second line (B. strataria); white, strigulated and densely peppered with black (B. betularia), or almost entirely black (melanic B. betularia); with a clear discal mark (dark), or without a clear discal mark. Forewings of the male without a fovea. Hindwings conspicuously patterned; whitish, peppered grey (especially basally), tinged reddish outside the second line (B. strataria); white, densely peppered and lined with black (B. betularia), or mainly black (melanic B. betularia); with a clear discal mark (perhaps, in B. betularia), or without a clear discal mark; transversely lined (B. strataria with no first line but a clear median, the outer lines more or less detectable but usually incomplete in B. betularia).
Hindwings lacking a tubular vein 5. Vein 8 of the hindwings approximated to or anastomosed with the upper margin of the cell to the middle or beyond. Hindwing veins 6 and 7 separate.
Posterior tibiae of males 4-spurred.
The abdomen conspicuously patterned (speckled), or plain.
Early stages. Larvae feeding on foliage of Quercus, Ulmus, Betula, Salix, Fraxinus, etc.
British representation. 2 species; South-east England, Central-southern England, South-west England, English Midlands, Northern England, Southern Scotland, Northern Scotland, Wales, and Ireland. Living adults found March and April (B. strataria), or May and June. B. strataria (Oak Beauty); B. betularia (Peppered Moth).
Illustrations. • Biston betularia (Peppered Moth, typical and melanic forms), cf. Biston strataria (photos). • Alcis, Biston, Cleora, Cleorodes, Deileptenia, Fagivorina, Menophra, Ourapteryx, Peribatodes, Selidosema: Newman. • Oenochrominae and Ennominae: Kirby 47.
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 genera of Lepidoptera-Geometridae. Version: 8th June 2016. delta-intkey.com’.