There was an autumn day in 1968 when fog descended over the whole of Europe, and only Malta and the military airport in Rome were able to take incoming flights. Nightly newcomers at the enthusiasts' string of coastal light traps, from the Isles of Scilly to the Northumberland coast, tell a story that backs up trends going back for more than a decade. In the 2009 edition of the UK Moth Bible,scores of species described as “local” or relatively uncommon outside the south of England in the original book only six years earlier have headed north. Does this carry significance? The jury is out and is likely to remain so for a long time. Great movements of moths, butterflies and other insects have a long and complicated history. Vast numbers of immigrant clouded yellows turned the fields of Cornwall golden in 1877 and again in the fraught wartime summer of 1941; but the species, common across the Channel, has yet to establish a permanent hold in the UK. The dainty geranium bronze, on the other hand, has colonized the whole of continental Europe since a single female arrived in Majorca in 1990 in a box of pelargonium plants from South Africa. Climate change may play a part, but so may vigorous winds toward the end of the summer, northwards from the Sahara. Brussels may have warmed a little closer to Johannesburg temperatures, but the geranium bronze and its host plants had much less chance of hitching an overnight lift in the past. Excessive glee or doomy angst are the two things to avoid, for all that we in the media tend to report such subjects in terms of “amazing increases” or “extinction fears”. The greatest-ever expert on the comma butterfly, a vicar's wife called Emma Hutchinson, dealt with this well in 1881 when she calmed one of many such scares by assuring The Entomologist that Herefordshire had never had such a good “comma autumn” except in 1875 when “every blackberry bush was covered with specimens”. She was a calm and practical soul, who also told the magazine of her statistical methods: “For many years I have bribed those over whom I have no control in this parish to collect for me every larva and pupa they can find, and by this means I have preserved many thousands of this lovely butterfly.” The “MP for moths”, Madeline Moon, made the point nicely in the House of Commons when she caught the then prime minister's attention by praising the role in such matters of a man called Blair. A doctor on the Isle of Wight in the 1940s and 1950s, he monitored the arrival of new immigrant species way back then so efficiently that no fewer than three – Blair's mocha, Blair's shoulder-knot and Blair's wainscot are named after him. Emma is justly remembered in the same way, by the beautiful variant of the comma, form Hutchinsoni.
