Insects of Britain and Ireland: the genera of Lepidoptera-Geometridae
Adults. Crepuscular and nocturnal; relatively stout-bodied to slender-bodied. Antennae of males bipectinate; bipectinate to the apex. Face rough (with a tuft of scales).
Wingspan 36–50 mm. The outer margin of the forewing angulated; more or less scalloped. Forewings whitish ochreous or brownish, or pinkish-purplish, with dark transverse lines and a small, dark apical fascia; exhibiting a transparent discal scar; with a clear discal mark, or without a clear discal mark. The discal mark when present, conspicuously pale-centred and dark-ringed, or not dark-ringed. Forewings with a distinct median band (the band dark, in S. tetralunaria, but not sharply distinguished in colour from the basal fascia), or without a median band. Forewings of the male without a fovea. The outer margin of the hindwings rounded to angled; more or less scalloped. Hindwings conspicuously patterned to plain; coloured like the forewings, but less patterned; with a clear discal mark, or without a clear discal mark. The discal mark when present, conspicuously pale-centred and dark-ringed, or not dark-ringed. Hindwings transversely lined, or without transverse lines.
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.
Early stages. Larvae feeding on foliage of diverse deciduous trees and shrubs.
British representation. 3 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 to July (sometimes double brooded?). S. dentaria (Early Thorn), S. lunularia (Lunar Thorn), S. tetralunaria (Purple Thorn).
Illustrations. • ‘Thorns’ - Angerona, Apeira, Colotois, Crocallis, Ennomos, Odontopera, Selenia: Newman. • Ennominae (‘Thorns’, etc.): Kirby 46. • Assorted Ennominae (‘Thorns’, with larvae): Humphreys, 1860.
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’.