Hillside offers new hope for endangered butterfly

Butterfly Conservation has acquired Rough Bank in the Cotswolds and plans to reintroduce the large blue butterfly to the site, which is already home to four species of blue butterflies.

The large blue became extinct in the UK in 1979 and is globally threatened but, following the discovery of its unusual lifecycle relying on a species of red ant, it was successfully reintroduced at a few sites across southern England.

Butterfly Conservation hopes the Rough Bank reserve could become a flagship site for the species as it expands back into the Cotswolds.

Rough Bank overlooks the Slad Valley, a landscape brought to life by writer Laurie Lee in his autobiographical novel Cider with Rosie, and is made up of flower-rich grassland.

The large blue’s survival depends on a species of red ant. The butterfly’s caterpillars resemble ant grubs, tricking the red ant into carrying them into the ant nests.

Inside the nest they feed on ant grubs for up to two years, and when they transform into a chrysalis they ensure further protection by producing a song mimicking the queen ant.

The butterfly will be introduced as young caterpillars taken from existing colonies in Somerset and placed carefully to be adopted by the ants.