Saving the Large Blue
- Protecting the Large Blue butterfly
- Collard Hill, Somerset.
The largest and rarest butterfly in the UK, the Large Blue, became extinct in 1979. However, we've been working hard with a number of other organisations to help recover and reintroduce this wonderful species.
The Large Blue butterfly is the largest and rarest blue butterfly in the UK. It became extinct in the UK in 1979 due to complex changes in land management, but has been successfully reintroduced since 1983.
It is a European Protected Species and is a high conservation priority species with a UK Biodiversity Action Plan (BAP).
The National Trust is a vital partner in the recovery programme of the Large Blue, which now consists of a partnership of 23 organisations headed up by scientists from Oxford University and the Centre for Ecology and Hydrology (CEH).
Where are the Large Blues?
At present we manage four areas for Large Blues. There are two on the north Cornwall coast, one on the south edge of Dartmoor, and one on Collard Hill in the Somerset Polden hills. This is currently the only open-access site.
Encountering the Large Blue
Collard Hill is currently the only place that people can freely visit this fascinating and most beautiful butterfly. From early June to early July we run it as an open-access site.
It is dear to our hearts as we believe passionately in facilitating quality experiences with nature, which are enhanced here by a wonderful picnicking place that offers fantastic views over the Somerset Levels.
At present over 1,000 people visit the site during the season. The visitors include a wide variety of people, and nearly everyone manages to see the butterfly.
The hill tends to be quite busy on sunny weekends during the Large Blue season, so if you want peace and quiet, come early or late in the day. When the weather is hot Large Blues tend to be quite active at those times anyway.
How is the Large Blue doing at Collard Hill?
The Large Blue was introduced to Collard Hill in 2000, as a translocation from an established population a few miles away. Since then it has had a couple of difficult years, due to poor weather and difficulties in arranging appropriate grazing. It’s now doing well though, and its numbers are almost certainly set to increase.
The population is monitored by two methods. First, in suitable weather the Large Blue Ranger counts butterflies along a fixed route. Secondly, detailed counts of eggs are made after the flight season has finished.
The table shows the approximate adult population size, estimated from transect data:
Year Adult population size
The population is already one of the largest known in Europe and may increase further.
Of course, much depends on the weather, particularly during the flight season. Their flight season usually runs from early June to early July, with maximum numbers flying during the third week of June.
View one of Britain’s rarest and most beautiful butterflies in the wild
For full details on accessing the Large Blues at Collard Hill, including when to visit, where to park, download our vist PDF. Otherwise please call the Large Blue phone line (07824 820193) from early June through to mid-July.
For up to speed details please visit the Collard Hill Large Blue Blog.
Other websites that may interest you: