Clifden Nonpareil Catocala fraxini
Wingspan 75-95 mm.
This is the Victorian collector's classic all-time favourite, the 'Blue Underwing'. In the British Isles it was formerly resident in certain parts of Kent and Norfolk during the middle part of the 20th century, but it became extinct as a breeding species and for many years was only recorded as an occasional immigrant.
In recent years it has been increasing again and is now considered to be recolonising and once again is a breeding species in some southern counties.
The large greyish caterpillar feeds mainly on aspen (Populus tremulosa).