The large blue butterfly is a globally threatened lepidopteran species. Its current range extends across northern Spain, Italy, Greece, and southern Scandinavia. It is also a native to the UK where in 1979 it went extinct.
In the UK, the species was estimated to consist of 91 colonies during the time period from the late 1790s to the 1840s. Over the century that followed, the number of colonies fell and when censused in the 1950s, only 25 popluations were believed to remain. The population decline accelerated and by 1972 only two colonies remained. Those two colonies became extinct in 1979. In 1983, scientists imported large blue butterflies from Sweden in an effort to revive the former British population.
