How to Revive an Extinct Butterfly


Image from bbc

TreeHugger was invited to a press conference by Holland & Barrett to celebrate 25 years of conservation. The UK's largest health food store chain announced that the stores will be giving up plastic bags as of the new year and customers will be sold jute and cotton carrier bags instead. Kudos to Holland & Barrett; the more stores that give up the bag the fewer bags out there to pollute the world.

Also speaking at the event was a professor who told a fascinating story about how the Large Blue Butterfly has been saved from extinction. It's like a detective story--only with botanists instead of CSI.

holland jute

The story begins in 1979 when the large blue butterfly (Maculinea arion) was declared extinct in the UK. In 1950 there were 25 colonies in the UK and by 1979 there were none. Now there are 35 colonies.

The life cycle of the butterfly is very unusual. The caterpillars, after munching on wild thyme for 2 weeks, go underground and live in the nests of red ants for 11 months. Then they pupate and later emerge as butterflies.

Then in 1979 they disappeared. After 6 years of research, scientists discovered that the life cycle of the butterfly was dependent on a particular species of ant called Myrmica sabuleti and this ant had disappeared. This was due to changes in grazing patterns, disease in rabbits, and overgrown fields. It had been replaced by a new and different ant which was incompatible with the butterflies' cycle. Without the right ants: no more butterflies.


Professor Jeremy Thomas

In 1984 Professor Jeremy Thomas, who told the story in a very personable and interesting way, went to Sweden, with financial assistance from Holland & Barrett, to bring back a bunch of butterfly eggs to the UK. These were introduced into an area of the Dartmoor that had suitable grazing, with the help of the National Trust. The red ants increased and the large blue butterflies were re-established and spread naturally. Now there are large blues on 100 sites in 5 regions of the countryside.


Image from

Along with the revival of the butterfly came the revival of some declining rare plants. The pale heath violet increased by 100-fold. This was because the red ants are attracted to the viola seeds, chew them up and scatter them. So the violas started growing again.

Now a number of organisations are working to expand the spots for the butterflies in 25-30 new sites in Devon and Cornwall.

Professor Thomas thanked Holland & Barrett for their generous support of this project 25 years ago.

When asked, the CEO of Holland & Barrett said that he would continue to support the project although he wasn't too specific about how he would do this.

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