Large Heath Satyridae

Maps updated: April 2008

Coenonympha tullia polydama (Müller, 1764)

Description: Wingspan 35-40mm. This is a very variable species both across its range and within single populations. In N. Irish populations the upperside and underside of the forewing are mainly light orange. The underside of the hindwings are grey with a jagged edged white blotch. Also there is usually some white pupilled black eyespots, but this is very variable. Some specimens can have none, others can be heavily spotted. The strength of spotting is clinal from north (unspotted) to south (strongest spotting) in Britain and Ireland but also within individual colonies. N. Irish specimens are generally only lightly spotted.

Similar Species: The two heaths are readily identifiable by the orange uppersides. Whilst they differ in habitat preference there are sites where the two species can be seen together in the west of N. Ireland. Well marked Large Heaths should present no difficulty as the Small Heath never has prominent spots on the hindwing. Lightly spotted Large Heaths may be more difficult to distinguish but most specimens are larger.

Key Identification Features:

Sets:  male upperside male underside

Flight Period: Single-brooded from late June to mid August

Status: Confined to the north and west of N. Ireland especially in Tyrone, south Londonderry, and north Fermanagh. Only one population survives in Armagh and it has never been recorded from Down.

Ecology: A colonial species found on raised and blanket bog on gentle upland slopes. Adults move only small distances within the habitat. Males fly more than females and can even be active on sunless calm days. Adults mainly feed on flowers of cross-leaved heath Erica tetralix. The only confirmed larval foodplant in Britain is Hare's-tail Cottongrass Eriophorum vaginatum though others are reportedly used. Larvae overwinter in 3rd instar within plant tussocks. They can survive short duration flooding.

World Distribution: northern and central Europe as far south as southern Germany. Also Russia, Alaska, Canada and the western United States.

Caterpillar: 

 Thompson, R. S. & Nelson, B., 2003 (Oct 2). [In] The Butterflies and Moths of Northern Ireland
http://www.ulstermuseum.org.uk/lepidoptera/species.asp?item=5592

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