70.239 Selenia tetralunaria (Purple Thorn) 1919
fw: 17-23mm; bivoltine in south Apr-May, Jul-Aug, occasionally trivoltine Sep-Oct, univoltine in north May-Jun; various broadleaved trees; common in most of England and Wales, more local north of the Humber.
ID: Similar to S.lunularia (Lunar Thorn). Distinguished by presence of a dark central spot on hindwing upperside near termen in S.tetralunaria and its absence in S.lunularia; central silver crescent in median fascia of forewing is obviously larger in S.tetralunaria; distal edge of median fascia (distal cross-line) is nearly straight in its costal half in S.lunularia, distinctly bowed in S.tetralunaria; hindwing termen is deeply scalloped in S.lunularia, usually less so in S.tetralunaria.
Page published 04/03/2014 (§1-3) wings need flipping