Blue heaven! Rarest British butterfly makes a comeback
BrITAIN’S rarest butterfly is flying high again – almost 30 years after being declared extinct in the UK.
following a meticulous re-introduction programme, numbers of the endangered Large Blue species are at their highest since the 1930s.
More than 10,000 are flitting through the Gloucestershire and Somerset countryside – the biggest concentration known in the world.
The Large Blue’s unusual life cycle had threatened its survival. Vital to its success is a type of red ant that lives only on closely grazed hillsides and meadows.
Large Blue caterpillars ‘sing’ and release chemicals that fool Myrmica Sabuleti ants into thinking the caterpillars are ant grubs. The ants then pick up the caterpillars in their jaws and carry them underground into their nests.
for the next ten months, the caterpillars munch their way through the ants’ eggs and grubs before emerging as beautiful butterflies the next year.
The precise details of the Large Blue’s life cycle were discovered in the 1970s by Jeremy Thomas, an oxford University professor who spent six summers living with the butterflies and laying trails of Battenberg cake to attract the ants.
Unfortunately, his work came too late to save the native population in Britain.
Changes to grazing practices after the Second World War meant grassland became overgrown and too shady for the red ant and the Large Blue was pronounced extinct in 1979.
In 1984, Professor Thomas used Swedish stock to reintroduce the species to Devon. Since then, more than 50 former sites in the South West have been cleared and restored.
he said the project ‘demonstrates that we can reverse the decline of globally threatened species once we understand the driving factors’.
roger Mortlock, of the Gloucestershire Wildlife Trust, said the return of the butterfly was ‘fantastic news’.