A rare butterfly that had been missing from a nature reserve for more than a century has been reintroduced to the site.
The large heath butterfly has been brought back to Heysham Moss in Lancashire where it was last recorded at the beginning of the 20th Century.
Lancashire Wildlife Trust and Chester Zoo are repopulating the reserve using insects from nearby Winmarleigh Moss.
Butterflies were bred at the zoo before being released at Heysham Moss.
The zoo's biodiversity officer Sarah Bird said it had been "fascinating" to follow the butterfly's life cycle.
"We're extremely pleased that the pupae we have so carefully reared are now hatching at Heysham Moss, their new home," she said.
The Wildlife Trust's North Lancashire Reserves manager Reuben Neville added: "The large heath butterfly was formerly much more widespread in North West England, inhabiting lowland raised bog and occasionally blanket bog habitats.
"Now extinct in Cheshire, Greater Manchester and Merseyside, it hangs on in just two widely separated sites in Lancashire."
Extensive habitat management was undertaken by the trust, which purchased Heysham Moss in 2004, to ensure the reserve provides sufficient support for the butterflies.
Heysham Moss is a peat bog which is home to a wide range of plants and animals.
Much of the site is designated as a Site of Special Scientific Interest.