Golden Plusia Polychrysia moneta
Wingspan 32-37 mm.
One of the classic 'invasion' species, this moth was unknown in Britain before 1890, when it was discovered in south-east England. Since then, it has spread rapidly north-westwards, even into Scotland, although there are signs that it is decreasing its range again over the last few decades.
Generally a garden species, the larvae feed on varieties of Delphinium. It is on the wing from June into August, and can be attracted to light.