Damselflies don't sound like they'd do anything as dramatic as invading anywhere, and the dainty damselfly sounds like it would do so least of all. But that's what's happening in southern England, as several species of these delicate, smaller relatives of the dragonflies cross over from the continent and start establishing populations here.
The dainty damselfly, a flying matchstick of bright blue and black, is the latest of a number of new arrivals from Europe which are thought to have been brought to Britain by rising temperatures caused by climate change.
It is actually a returner, rather than a completely new species, as it bred in at least one site in Essex until the population was wiped out in the great floods of the winter of 1953. There was no further sighting for 57 years until four adults were observed and photographed recently in north Kent by two recorders for the British Dragonfly Society, Gill and John Brooks.
On the Continent, Coenagrion scitulum has a predominantly central and southern distribution, although there have been signs of a northerly expansion of its range. In the last fifteen years the dainty damselfly has recolonised Belgium after a long absence, and appeared for the first time ever in The Netherlands; it also appeared on Jersey in 2009.
Its appearance in Britain is significant as it follows the establishment of other unusual damselflies in southern England over the last decade or so. The small red-eyed damselfly, now a common breeding species in much of south-east England, first appeared in Britain only as recently as 1999, while the willow emerald damselfly appeared in 2007 and may now be established in Suffolk.
The British Dragonfly Society comments that "these events, which for Britain's dragonfly fauna are pretty much unprecedented, are thought likely to be a consequence of ongoing climate change, and many species with a primarily Mediterranean distribution in Europe are indeed known to now be advancing northwards."
In fact, the march of the damselflies is only one aspect of a much wider, continuing invasion of southern Britain, possibly caused by the warming climate, by a range of continental creatures which can fly – both insects and birds. Insects in particular are flooding in, and over the past decade a whole series of continental bees, wasps, moths, butterflies, dragonflies and grasshoppers has appeared here
At least one new continental dragonfly species, the lesser emperor, is now seen in Britain every year and is thought to have established a population at Dungeness, while others, such as the brilliantly-coloured scarlet darter, are waiting in the wings and could cross the Channel and start breeding here very soon.
This happened last year with an attractive continental butterfly species, the Queen of Spain fritillary, which crossed over from Normandy to Sussex – thought to be only about a six-hour flight for a butterfly – and set up a breeding population near Chichester. Other continental butterfly migrants such as the clouded yellow and the red admiral are now managing to survive over winter, while we are increasingly seeing the charming hummingbird hawk-moth, which does indeed look just like a hummingbird as it moves in and out of flowers, seeking nectar.
European bees and wasps are also arriving. Perhaps the most dramatic arrival is the large, deep-blue, alarming-looking but harmless, violet carpenter bee, Europe's biggest, which began breeding in a dead Bramley apple tree in a garden near Leicester three years ago. A rather less scary arrival is a bumblebee, the brown-banded carder bee, which has now begun breeding on brownfield sites in the Thames estuary.
Several continental bees and wasps now in the UK are so unfamiliar that they do not even have English names, such as the large social wasp Dolichovespula media, which created concern among gardeners when it arrived in the UK in about 2000 because of its size. Other wasps that have recently come into the country include the bee-wolf, which hunts bees for food, and the French spider-eating wasp Episyron gallicum.
But it's not just insects crossing the channel to join us. A number of bird species have moved in, including the little egret in 1996 and the cattle egret in 2008, while this year, the purple heron bred successfully in Britain for the first time. Other species that may well establish themselves include the great reed warbler, the black kite, the black-winged stilt and the serin.