Dark Crimson Underwing Catocala sponsa
Wingspan 60-70 mm.
A rare species, classed as Red Data Book category RDB3. It occurs as a breeding species only in the New Forest, Hampshire, and otherwise is only occasionally recorded as a migrant.
The adults are nocturnal and can be attracted by sugar as well as light. There is one generation during the year, flying in August and September.
The larvae feed on oak (Quercus).