A rare but fairly distinctive species, distinguished from the more common P. crepusculella by the absence of a partial fascia on the costa. Restricted to a very few sites in the fens and broads of Norfolk and Cambridgeshire, until the surprise finding of a colony at Orlestone, Kent in 2020 (Boothroyd, B in Atropos: 66).
Previously thought to have been a miner of the stems of Marsh Marigold, studies in the Netherlands (van Nieukerken, in 2006 Franje 9(17) and Huisman et al. 2007, in Entomologische Berichten 67) indicate that Gypsywort Lycopus europaeus is the food plant, borne out by field observations in Norfolk, and the recent reports from Kent, where Gypsywort is abundant on site.