Swallow-tailed Moth Ourapteryx sambucaria
Wingspan 40-50 mm.
A spectacular species and one of our largest Geometrids, this is however reasonably common in Britain, except for northern Scotland where it is local or absent.
Being strictly nocturnal and having quite a short emergence period in July, it is not often encountered by the non-enthusiast.
The larvae feed on a number of trees and shrubs, but prefer ivy (Hedera helix).