British status uncertain: possibly accidentally imported. Apart from one which was caught near Bristol in 1815 and a few other 19th Century records of dubious providence, a slightly worn male was taken at rest on a tree-trunk in Leigh Woods, Somerset, not far from the port of Bristol, in July 1949, and was later reliably identified. Not recorded in Hampshire or on the Isle of Wight to date. Wingspan 50-58 mm. The most likely confusion species are
Grey Arches Polia nebulosa which resembles it in size and prominence of the stigmata, but is grey or blackish, and
Light Arches Apamea lithoxylaea, which is of similar size and colour, but lacks prominent stigmata; both these species lack dark spots on the hindwing (MBGBI Vol 10). Larva feeds on Blackthorn, Wych Elm and English Elm, no evidence of breeding in the UK.