Langmaid's Yellow Underwing Noctua janthina
[Denis & Schiffermüller], 1775
Wingspan c. 35 mm.
This species and N. janthe were only separated as different species in 1991. This moth was then discovered for the first time in Britain shortly afterwards, at Southsea in Hampshire. Subsequently it has been noted on a number of occasions generally in the south of the country.
One of the distinguishing features is the extent of the black border on the hindwing, which in the present species, is very broad and complete such that the yellow shows just as a central small patch. However this is not sufficient alone to confirm the identity, and the underside of the forewing should also be checked to ensure there is no finger-like projection of the black area into the yellow suffusion.
The species flies in July and August, and it is possible that there is a slightly earlier emergence period than N. janthe, although this has yet to be confirmed.