Scientists to attempt to rear swallowtail butterflies from eggs frozen in nitrogen

In 2024, the British swallowtail suffered its worst year since scientific records began. Photograph: Iain H Leach/PA

Researchers are to attempt to rear swallowtail butterflies from eggs frozen in liquid nitrogen in a test to see whether cryopreservation could support the long-term conservation of Britain’s largest native species.

In a groundbreaking project, researchers will freeze eggs of captive-bred European swallowtails in liquid nitrogen at -196C and attempt to rear butterflies from the unfrozen eggs, comparing their success with butterflies reared from eggs that have never been frozen.