A rare butterfly is back in Britain and thriving for the first time in years.
The large blue, which is endangered in Europe, has returned to the UK after a special breeding programme got them laying eggs and hatching again.
The species died out in Britain in 1979 but was reintroduced at secret sites around the UK in 1983, using large blue caterpillars from Sweden.
This summer 10,000 butterflies were spotted in the UK and experts hope the species is now back for good.
The large blue died out because it needs the right food and a lot of luck to survive.
The species only lay their eggs in wild thyme flowers - which the caterpillar eats once it has hatched.
The grub then drops to the floor where, if it's lucky, it will meet a Myrmica sabuleti red ant which will adopt it. The ant will then carry it back to its nest where the caterpillar becomes a chrysalis before turning into a butterfly.
The way the butterfly was brought back to Britain could be used by conservation groups to bring back other animals.
An expert from the Butterfly Conservation, the charity behind the plan said "It is a fantastic success."