Portland Bird Observatory - wildlife diary

This photo-page illustrates the three specimens of Langmaid's Yellow Underwing Noctua janthina taken at Portland Bill in August 2003 and compares them with specimens of Lesser Broad-bordered Yellow Underwing Noctua janthe. Whilst two of the specimens would seem to be unequivocally janthina, the third (the least worn of the two specimens taken on 6th August) appears on balance also to be that species - it's identity remains to be fully confirmed by dissection.

In addition to the published identification criteria, the following apparent differences between these three janthina and specimens of janthe were noted:

At rest, the janthina were somewhat shorter and broader winged than janthe.
All three specimens had less contrastingly banded legs than most janthe.
The subterminal line on the upperside forewing of janthina was smoother and distinctly less 'jagged' than the same line on janthe.
The distal edge of the postmedian band was more acutely angled on janthina than it was on janthe.

Two Langmaid's Yellow Underwings (left and right) and a Lesser Broad-bordered Yellow Underwing (centre) - Portland Bill, 6th August 2003

Two Langmaid's Yellow Underwings - Portland Bill, 6th August 2003

Langmaid's Yellow Underwing - Portland Bill, 6th August 2003

Langmaid's Yellow Underwings - Portland Bill, 5th August 2003 (top) and 6th August 2003 (centre and bottom)

Lesser Broad-bordered Yellow Underwings - Portland Bill, 6th August 2003 (top) and 19th July 2002 (bottom)