The main foodplant of the larvae of the large heath is hare's-tail cottongrass (Eriophorum vaginatum) or occasionally common cottongrass (Eriophorum angustifolium) and the adult butterflies are, therefore, found on wet grassland or moorland. The distribution of the large heath is restricted to wet boggy habitats in northern Britain, Ireland, and a few isolated sites in Wales and central England. It is, however, widely distributed throughout the Outer Hebrides.
IUCN (2001) - Vulnerable
Scottish Biodiversity List of species of conservation importance
The adults always sit with their wings closed and can fly even in quite dull weather provided the air temperature is higher than 14C. The size of the underwing spots varies across its range: from a a heavily spotted form in the south to a virtually spotless form in northern Scotland. Therefore, in the Outer Hebrides they can appear very similar to the small heath (Coenonympha pamphilus), although size is a distinguishing factor.