A rare Red Data Book species, in ancient oak woodland in parts of southern England, a priority species under the UK Biodiversity Action Plan. It is now confined to the New Forest and two large woodlands in south Wiltshire. There are also occasional records near the south coast between Dorset and Kent, which may refer to migrants. In Hampshire and on the Isle of Wight now confined to the New Forest; formerly more widespread, including a few records from vice-county 12, and there are two records from the Isle of Wight, in 1979 and 1982. Wingspan 50-66 mm. The most likely confusion species are Red Underwing C. nupta
and Dark Crimson Underwing C. sponsa
, which see for differences. Larva feeds on Pedunculate Oak and Sessile Oak, over-wintering as an egg.