The Heath Fritillary (Melitaea athalia) is a butterfly of the Nymphalidae family. It is found throughout the Palaearctic from Western Europe to Japan, in heathland, grassland, and in coppiced woodland. Its association with coppiced woodland earned it the name "Woodman's Follower" in parts of the UK (Butterfly Conservation, n.d.). It is considered a threatened species in the UK and Germany, but not globally.
- See glossary for terms used
Heath Fritillaries have a wing-span of 39–47 mm (Warren & Emmet, 1990). The upperside is predominantly dark brown and orange-brown, with the orange-brown spots delineated by dark brown (along and across the wing-veins); there is a white fringe to the wings through which the dark brown extends. The upperside of the body is a similar dark brown to the colour on the wing, and the base of both wings is dark brown. The underside shows bands of red and (off-)white, again with each vein dark brown and each colour delineated by dark brown. The pattern of white spots at the base of the hindwing (visible at rest) is diagnostic for identification.
In the UK, the Heath Fritillary is restricted to Cornwall and Devon grasslands (abandoned hay-meadows); Exmoor (heathland); and Kent and Essex (coppiced woodland on acid soils) (Tomlinson & Still, 2002). The populations in Essex are the result of reintroductions (Warren & Emmet, 1990), and further reintroductions are ongoing in various other parts of the UK (Chandler, 2005). In the late 1990s, the species was estimated to occupy just 0.2% within the 10-km grid squares over the whole of its UK range (Cowley et al., 1999).
Overall, it ranges throughout the Palaearctic region from Western Europe to Japan (Warren & Emmet, 1990). In Europe, it is absent from Iceland, Ireland, Scotland, Wales, southern Portugal, southern Spain, the Mediterranean islands and southern Greece (Tolman & Lewington, 1997).
Its altitudinal range is from sea-level to 2600 m (Tolman & Lewington, 1997).
Heath Fritillary is not listed on the IUCN Red List (IUCN, 2006), suggesting that globally it is not considered threatened.
In the UK, however, the species was "considered to be the most endangered British butterfly" after a nationwide survey in 1980 found only 31 surviving colonies. Consequently, it was given protection under the Wildlife and Countryside Act 1981 (Warren & Emmet, 1990). Despite subsequent widespread efforts to conserve and manage the species' habitats, it has continued to decline: distribution has declined 25% since the 1970s, and abundance-wise it declined by 46% in the 10 years 1995–2004 (Butterfly Conservation, 2007). Woodland sites in Kent and Essex are actively managed (coppiced) for the conservation of this species. It has been a "high priority" species in the UK Biodiversity Action Plan (BAP) since 1995 and has its own Species Action Plan (Barnett & Warren, 1995).
In England, this species occupies three distinct habitats (Tomlinson & Still, 2002; Warren & Emmet, 1990; Butterfly Conservation, n.d.):
- Unimproved grassland with abundant short (5–15 cm) or sparse swards of Ribwort Plantain or Germander Speedwell (or both) on stony soils – sometimes in the form of abandoned hay-meadows
- Sheltered heathland with Common Cow-wheat scattered among Bilberry-dominated vegetation – valleys with mineral soils
- Coppiced woodland (especially in clearings) with Common Cow-wheat on acid soils.
Heath Fritillaries typically fly close to the ground, with characteristic "flits" and glides. Colonies tend to be compact, centred on favoured breeding areas. Heath Fritillaries are highly sedentary for the most part, adults rarely moving more than 100 m; however, some have been recorded dispersing up to 2 km. For a species of often short-lived habitats, it has remarkably limited colonizing ability; suitable habitats over 600 m from an existing colony are colonized slowly (Butterfly Conservation, n.d.).
The female Heath Fritillary lays its eggs (or ova) in batches of (15–)80–150 on the underside of leaf of a larval food plant or on a plant adjacent to the larval foodplant.
Eggs are oval spheroids with flattened bases, about 0.5 mm high. They are ribbed (longitudinally, i.e. from top to bottom) and striated (transversely, i.e. around the egg). Pale cream when laid, eggs darken to pale yellow within 2 days, and then dark grey a few days before hatching. Eggs mature in 2–3 weeks. (Warren & Emmet, 1990)
Upon emergence, first-instar caterpillars (or larvae) eat their eggshells. The caterpillars from a clutch initially stay together, feeding in a small, unobtrusive web. Second or third-instar caterpillars disperse into smaller groups. Then the third instars tend to feed and rest solitarily; they rest beneath dead leaves at night and during bad weather. The caterpillar hibernates for the winter in a hibernaculum, made from a curled dead leaf by spinning its edges together. Hibernacula are usually close to the ground. Although most caterpillars hibernate singly, they sometimes group in twos and threes, although 15–20 caterpillars have been found in single hibernaculum. (Warren & Emmet, 1990)
Caterpillars re-emerge in early spring. When it is warm, they feed a little, but most of the time is spent basking in the sun. There are six instars in total. The full-grown sixth instar caterpillar is 22–25 mm long, and predominantly black; it has pale (yellow-orange) spines and (greyish-white) spots. (Warren & Emmet, 1990; Tomlinson & Still, 2002)
The pupae are 12.4–12.8 cm long and last 15–25 days (early May to late June in the UK). They are white with black and orange-brown blotches. Pupae are usually found close to the ground in or beneath dead leaves. (Warren & Emmet, 1990; Tomlinson & Still, 2002)
A study in Cornwall (England) recorded mortality rates in the region of 50%, mostly from predation by small mammals, but including predation by beetles, and parasitism (Warren, 1985, cited in Warren and Emmet, 1990).
Imagines probably live for 5–10 days (Warren & Emmet, 1990). Males are active on warm sunny days. Females mate once shortly after emerging; they lay their eggs only during warm weather, spending most of the time either basking or hiding in vegetation. (Warren & Emmet, 1990; Tomlinson & Still, 2002)
In the UK, the flight period is from the end of May to the beginning of July (in the south-west) and early June to early August (in the south-east) (Warren & Emmet, 1990).
In the UK, the following species are used (Warren & Emmet, 1990):
- Common Cow-wheat (Melampyrum pratense) — the only foodplant in woodland, and principal foodplant on heathland
- Common Foxglove (Digitalis purpurea) — secondary foodplant on heathland
- Ribwort Plantain (Plantago lanceolata) — major foodplant on grassland
- Germander Speedwell (Veronica chamaedryas) — major foodplant on grassland
- Greater Plantain (P. major) — secondary foodplant
- Ivy-leaved Speedwell (V. hederifolia) — secondary foodplant
- Thyme-leaved Speedwell (V. serpyllifolia) — secondary foodplant
- Yarrow (Achillea millefolium) — secondary foodplant
- Barnett, L.K. & Warren, M.S. (1995) Species Action Plan: Heath Fritillary Mellicta athalia. Butterfly Conservation, East Lulworth, UK. 24p.
- Butterfly Conservation (n.d.) Heath Fritillary Melitaea athalia factsheet. Butterfly Conservation, East Lulworth, UK. 2p.
- Butterfly Conservation (2007) The State of Britain's Butterflies 2007. Butterfly Conservation, East Lulworth, UK. 12p.
- Chandler, D. (2005) The fritillaries of Herts & Middlesex in the summer of 2005. Butterfly Conservation Hertfordshire and Middlesex Branch Newsletter 43 (September 2005): 1–3.
- Cowley, M.J.R., Thomas, C.D., Thomas, J.A. & Warren, M.S. (1999) Flight areas of British butterflies: assessing species status and decline. Proceedings of the Royal Society of London B 266: 1587–1592.
- IUCN (2006) IUCN Red List of Threatened Species. (www.iucnredlist.org) (Accessed on 15 June 2007)
- Tolman, T. & Lewington, R. (1997) Collins Field Guide: Butterflies of Britain & Europe. HarperCollins, London, UK. pp. 174–176.
- Tomlinson, D. & Still, R. (2002) Britain's Butterflies. WildGuides, Old Basing, UK. pp. 124–125.
- Warren, M.S. & Emmet, A.M. (1990) MELLICTA ATHALIA (Rottemburg). Pages 241–243 in Emmet, A.M., J. Heath et al. (ed.) The Butterflies of Great Britain and Ireland. The Moths and Butterflies of Great Britain and Ireland Vol. 7 Part 1 (Hesperiidae to Nymphalidae). Harley Books, Colchester, UK.