Blues revival

Thousands of one of Britain's most spectacular butterflies, which became extinct in the country in 1979, flew again this summer as a result of a careful research, reintroduction and conservation programme that provides a model for other flagship species. The British Large Blue (Maculinea arion) occurs across Europe and northern Asia and is one of six large blue species globally, all of which are in serious decline. The beautiful butterfly was highly prized by Victorian collectors, but they were constantly frustrated by their inability to raise it in captivity. It was not until the early years of the last century that detailed observations Detailed ecological research three decades ago is now paying dividends for one British butterfly. Nigel Williams reports. Blues revival unravelled the problem. Three leading lepidopterists discovered that, after feeding on wild thyme flowers for about three weeks, the small caterpillars crawled or fell to the ground. Here they awaited discovery by a red ant of the genus Myrmica, which began feeding on a sugary solution secreted from special glands on the caterpillar's back in response to the ant's attention. Movements by the caterpillar then prompted the ant to carry it underground into its nest. Here, the caterpillar began feeding on ant grubs. In the late spring of the following year the caterpillar pupated and after three weeks the butterfly emerged and crawled out of the ants' nest. But these insights into the complexity of the lifestyle of these butterflies did not stop the steady decline of the species nationally. Concerned conservationists established nature reserves which they fenced off to prevent livestock damaging the thyme and installed wardens to deter collectors who were perceived as the main cause of local extinctions. But the butterfly continued to disappear. By 1972 the butterfly had gone from most of its former sites and only two colonies in southwest England remained. Conservationists were now deeply concerned and decided to commission further work to see if there were more aspects of the biology of this species that had been overlooked. The then Nature Conservancy Council (now Natural England) and the Institute of Terrestrial Ecology (now the Centre for Ecology and Hydrology) appointed a young researcher, Jeremy Thomas, to further investigate the problem. But the timing was difficult, with his first field season turning out to be the last for the Cornish colony of Large Blues and at the other site in Devon only …