73.124 Hydraecia petasitis (Butterbur)
ws: 40-52mm (MBGBI10), fw: 19-23mm (Waring & Townsend); Aug-Sep; Butterbur (Petasites hybridus); local along riverbanks and ditches mainly from the Wirral and the Humber north to the Scottish borders, very local in river valleys and flood plains of CS.England.
ID: Similar to H.micacea (Rosy Rustic) but averages larger and is brown. H.micacea is most often noticeably smaller and reddish, but some specimens are large and brown - such specimens may be distinguished by the subterminal line which though indistinct is substantially more dentate in H.petasitis. H.petasitis is never found far from the foodplant - but in my experience H.micacea is much more common than H.petasitis even when a light-trap is set within a clump of Butterbur.
§1 Bampton Grange, Cumbria; 03/09/2022; female; fw 22.0mm
§2 Bampton Grange, Cumbria; 03/09/2022; male; fw 19.8mm
§3 Bampton Grange, Cumbria; 30/08/2022; female; fw 20.5mm
All images © Chris Lewis
§2 Bampton Grange, Cumbria; 03/09/2022; male; fw 19.8mm
§3 Bampton Grange, Cumbria; 30/08/2022; female; fw 20.5mm
All images © Chris Lewis
Page published 08/09/2022 (§1) | §2&3 and dissection images of §1 added 30/11/2022