A species of bee not seen in Britain for a quarter of a century is being reintroduced to the countryside there.
The short-haired bumblebee was once widespread across the south of England, but it vanished in 1988.
However, after a healthy stock of the bees was found in Sweden, conservationists were able to collect some to seed a new UK colony.
About 50 queen bumblebees are being released at the RSPB's Dungeness reserve in Kent.
Before their release, the bees were put in quarantine for two weeks at Royal Holloway, University of London.
The loss of the short-haired bumblebee (Bombus subterraneus) was caused by a dramatic decline of wildflower meadows that occurred after World War II as agriculture intensified to feed the growing population.
It is estimated that 97% of Britain's flower-rich grasslands, which the bees needed to forage and thrive, has vanished over the past 70 years.
But the BBC reports the species is doing much better in southern Sweden as fewer people live there and farming practices are more bee-friendly.
"The bee population in Sweden is expanding and growing whereas for everywhere else in Europe it has been contracting - it is either rare, threatened, or extinct like in the UK.'' said Dr Nikki Gammans.
"So Sweden was really the only place we could go to collect the bees."
Farmers have also been involved in the project, which has been funded by Natural England, the RSPB, Hymettus and the Bumblebee Conservation Trust.
By leaving margins unfarmed at the edges of their fields, flower-rich, green "corridors" are created, which will help the bees to spread out across the area.
Previous attempt failed
This is the second attempt to release the short-haired bumblebee in Britain.
In 2009, Dr Gammans collected bees from New Zealand, which were introduced there from the UK in 1895 to pollinate red clover.
But DNA tests found the colony lacked genetic diversity and many of the queens did not survive their hibernation once in the UK.
But Dr Gammans is much more optimistic about the success of the Swedish bees.
''We think there will be a really good chance that it will establish, it will become self sustainable and spread," she said.
Dr Gammans said she expected between 20-30% of the reintroduced queen bees would survive after their release and create nests.