The Large Heath is restricted to wet boggy habitats in northern Britain, Ireland, and a few isolated sites in Wales and central England.
The adults always sit with their wings closed and can fly even in quite dull weather provided the air temperature is higher than 14B:C. The size of the underwing spots varies across its range; a heavily spotted form (davus) is found in lowland England, a virtually spotless race (scotica) in northern Scotland, and a range of intermediate races elsewhere (referred to as polydama).
The butterfly widespread on many bogs in Scotland.
Size and Family
- Family: Browns
- Size: Small/Medium
- Wing Span Range (male to female): 41mm
The main foodplant is Hare's-tail Cottongrass (Eriophorum vaginatum) but larvae have been found occasionally on Common Cottongrass (E. angustifolium) and Jointed Rush (Juncus articulatus). Early literature references to White Beak-sedge (Rhyncospora alba), are probably erroneous.
The butterflies breed in open, wet areas where the foodplant grows, this includes habitats such as; lowland raised bogs, upland blanket bogs and damp acidic moorland. Sites are usually below 500m (600m in the far north) and have a base of Sphagnum moss interspersed with the foodplant and abundant Cross-leaved Heath (the main adult nectar source).
In Ireland, the butterfly can be found where manual peat extraction has lowered the surface of the bog, creating damp areas with local concentrations of foodplant.