The Large Blue butterfly is one of the worlds most threatened species. The British reintroduction was based on major scientific breakthroughs, and the development of a pioneering model for conservation which is now being used to restore rare butterfly species across Europe.
The Large Blue has an unusual life-cycle, which made its conservation difficult. When the caterpillar is three weeks old it tricks red ants into believing it is one of their own grubs and is taken underground to be placed with the ant brood. The caterpillar spends the next ten months feeding on the grubs before pupating in the nest the following year and then emerging to crawl above ground as a butterfly.
Dr Christopher Hancock from Somerset Wildlife Trust, said: "The sustained growth of the large blue population at Green Down since its introduction in 1992 has been far beyond our expectations and we now host the largest known colony in the world.
This enables us to provide the breeding stock for introductions elsewhere in England. This is all a remarkable achievement for Somerset by the dedicated staff, the grazier, volunteers and partners involved in the management of the site."