Insects - Butterflies


Image above by Iain Leach
High brown fritillary Argynnis adippe - Critically endangered

This majestic fast flier was once found across much of England and Wales but reflecting a 96% decline in its distribution since the 1970s, it has become the UK’s fastest declining butterfly. Dartmoor and Exmoor are national strongholds. In Devon this butterfly favours bracken-dominated habitats on south facing slopes on the edges of the moors. The larvae feed on common dog violet and occasionally on a few other violet species. In 2019, on Dartmoor, High Brown Fritillaries were recorded at nine sites, and numbers have risen in the last two or three years. Habitat condition at the key sites in the Dart Valley is improving, thanks to efforts by the Devon Wildlife Trust reserve volunteers and 'All the Moor Butterflies' team, who have carried out targeted management work. On Exmoor, High Brown Fritillary was recorded at six sites in 2019. However, numbers here have fallen in the last two years despite significant management effort. It is hoped that this situation will improve with the introduction of grazing to a key area of breeding habitat in the Heddon Valley. The species is threatened by a decline in grazing or swaling (moor burning) leading to the development of rank vegetation and scrub.

Further information on this species can be found here.

Map to show the Devon distribution of this species


Image above by Iain Leach


Pearl-bordered fritillary Boloria euphrosyne - Endangered

Once very widespread across Britain, the Pearl-bordered Fritillary is now largely restricted to the northern half of Scotland, south Cumbria, Devon and Cornwall, and the woodlands of South East England. Devon is a national stronghold. Here it mainly occupies rough grassy or heathy slopes with bracken, often within woodland or scrubland settings. The foodplant for the larvae is common dog violet and occasionally other violet species. The butterfly has recently been recorded at 37 sites on Dartmoor and populations are considered stable here: they are also doing well at the Devon Wildlife Trust's Marsland reserve where there has long been active management for the species. It is threatened by changes in grazing and burning practices, especially cessation, by scrub invasion and by habitat fragmentation.

Further information on this species can be found here.

Map to show the Devon distribution of this species


Image above by Iain Leach


Marsh fritillary Euphydryas aurinia - Vulnerable

Historically, this butterfly has experienced large declines in range and abundance. However, it still has numerous colonies in south-west England, western Wales, western Scotland and Ireland. Devon is considered a national stronghold, especially Rhôs pastures on Dartmoor and the Culm grasslands of the north-west of the county. It occupies wet grasslands and fen meadows where the caterpillar foodplant, Devil's-bit scabious, is frequent. Another Devon Special Species, the Narrow-bordered Bee Hawkmoth, occupies the same habitat and uses the same larval foodplant. Over the last two decades Butterfly Conservation and the Devon Wildlife Trust have worked to safeguard sites for this butterfly and improve their condition. Recently marsh fritillaries have been recorded at 31 sites on Dartmoor, and both here and on the Culm, populations are considered stable, although numbers fluctuate considerably from year to year. Threats include changes in grazing and burning management, scrub invasion, and habitat fragmentation: it is prone to local extinction and if sites are distant it is unlikely re-colonisation will occur.

Further information on this species can be found here.

Map to show the Devon distribution of this species


Image above by Bob Eade
Wood white Leptidea sinapis - Endangered

Devon is an important national stronghold for this dainty butterfly, one that is declining nationally. In Devon there is an exceptionally large colony at Meeth Quarry nature reserve, a strong population in the plantations of Cookworthy Forest, and atypical colonies on the Undercliffs of the East Devon coast - here the butterflies use a habitat unlike any other in the UK. The butterfly inhabits sunny woodland rides and glades, and mosaics of shrub, tall grassland and overgrown hedgerows. Both Meeth Quarry and the Cookworthy Forest complex are being actively managed for the butterfly by the Devon Wildlife Trust and Forestry England respectively, and it is doing well in both places. Populations are probably currently stable in Devon as a result of conservation effort, but it is vulnerable to unfavourable changes in site management and to any further habitat fragmentation.

Map to show the Devon distribution of this species


Image above by Iain Leach


Brown hairstreak Thecla betulae - Vulnerable

Declining nationally, Devon is a major British stronghold for this elusive butterfly: it remains fairly well distributed across the county. A species of hedges, scrub and woodland edge, the eggs are laid on the young growth of blackthorn, the foodplant of the caterpillars. The main reason for its decline is believed to be the tight annual flailing of hedgerows which destroys the eggs. Many hedges remain unfavourably managed for the butterfly in Devon, although agri-environment schemes like Countryside Stewardship have helped reduce the frequency of trimming. Reflecting its elusive nature as an adult, the species is under recorded and more effort is required to determine its status across Devon.

Map to show the Devon distribution of this species

Further sources of information:

Butterfly Conservation

Devon Branch of Butterfly Conservation

All the Moors Butterflies