6 September 2010
The Large blue butterfly became extinct in England in 1979. Subsequent re-introductions from Sweden have established colonies in Devon, Cornwall, Somerset and Gloucestershire. The caterpillar feeds in the flowers of Thyme and Marjoram, later leaving the plant and being taken into the nest of the red ant, Myrmica sabuleti. There it is fed on ant grubs until it pupates.
Latin name: Glaucopsyche (Maculinea) arion
Previously found over much of southern England, its populations declined through intensification of grassland management and abandonment of low-productivity pastures. The last colonies also suffered from over-collecting until the final colony died out in Devon. Following a lengthy investigation into its ecological requirements and a series of trial releases, the butterfly is present on a number of sites, some of which support strong populations.
Where to see and when:
Adult butterflies can be seen from mid May until the middle of June. Access is not permitted on most sites during the flight period but the National Trust welcome visitors to the thriving colony at Collard Hill in Somerset.
What’s being done:
New sites are being restored in Devon, Cornwall, Somerset and Gloucestershire for natural colonisation or introduction of the large blues as soon as conditions are right. Existing colonies are monitored every year and ecological research into detailed aspects of its habitat requirements continues.