NATURE: Where have all our butterflies gone?

‘Record low butterfly numbers so far in annual count’; ‘Butterfly populations in trouble across Ireland and Britain’; ‘Butterfly numbers plunge in annual Dutch garden count’. Such headlines are all too common. But why are we beset by such things?
Some are quick to blame the poor weather of the last year or two. Others blame environmental shifts, such as climate change or a lack of proper food plants.
Whatever the real reason, we hardly raise an eyebrow anymore. We sit as frogs in the proverbial pot, scarcely aware of rising heat. Yet with little effort we could take the small steps needed to keep these lovely flying creatures for the next generation.
Fifty years ago, when I was a lad, almost every patch of stinging nettles we found was festooned with caterpillars of tortoiseshell, peacock and red admiral. We watched with interest as some spun silken nests and others constructed tent cities, folding leaves and sewing them together to form simple but effective shelters. Communities worked together for the betterment of all, and ate and grew along the way, shedding dark and wrinkled skins galore, which we gathered and gazed at in the wonder of our childhood paradise.
With its bold red, black and white markings, the red admiral, Vanessa Atalanta, must be one of everybody’s favourites. (Names have meanings: Vanessa is Greek for butterfly; Atalanta was a very lovely and fleet-footed maiden who was raised by a bear after being abandoned by her father, who wanted a son rather than a daughter. Carl Linnaeus, the Swedish physician who sought to scientifically describe all living things he encountered, was a poet as well as a prominent biologist.)
Each spring, clouds of red admirals gather in their native lands throughout southern Europe and North Africa, waiting for the right wind to carry them across the Mediterranean Sea, the English Channel or the Irish Sea and beyond.
In some years they travel in small groups. In others, a mass irruption occurs when large numbers of these long distance migrants congregate and depart as one thick flock many thousands strong. Such events once brought to our shores one of the greatest events in the natural history of this country, when huge clouds of butterflies appeared overnight, as if out of nowhere.
Spring still brings the greatest migration, when newly emerged adults are eager to conquer new territories. We don’t get to see these at their best, for they have travelled many miles on delicate wings. From the moment they crawl from their chrysalis homes, butterfly wings lose colourful scales and by the time our first red admiral migrants arrive in May or June they often wear bare, semi-transparent patches.
In recent years we see these early arrivals only in small numbers, one here and two, perhaps, somewhere else. Still, once here they begin to reproduce. Eggs of astonishing and symmetrical beauty are laid singly on the upper side of young nettle leaves. Given fair weather, these might hatch in a week or so. The newly emerged caterpillar sets about the all-important business of eating, pausing just long enough to slip out of a too-tight skin every few days.
As the creature grows it takes time out to increase the size of its dwelling, securing folds of nettle leaf within which it takes rest. Indeed, it is within the confines of this self-build that it becomes first a buff-coloured chrysalis, and then a mature and very glamorous insect.
For many years we thought we knew: all red admirals that made it this far north or were bred in this part of the world died at the onset of winter. In recent times, reverse migrations were spotted, with Irish-bred adults encountered along regular southbound migration routes.
Still, scientists insisted that these creatures were incapable of surviving the cold damp of an Irish winter. Now we know differently. Some adult red admirals do remain with us, though it is still thought they don’t hibernate as do small tortoiseshell and brimstone butterflies.
Perhaps our changing climate is altering the behaviour of these, as well as of our other wildlife.
Even if climate was entirely responsible for the shortage of these butterflies, we could do something to help. Red admirals need stinging nettles if they are to thrive. Yet what do most of us do should said nettles be growing on our own property, or nearby?
Cut them down or trample them into the ground. Worse still, spray them. Why not leave them instead?
While giant strides are needed, small steps will lead the way.

Michael Kingdon, a naturalist and keen fisherman, lives on the shores of Mayo’s Lough Carra, the best example of a shallow marl lake in western Europe, and therefore an SAC of enormous ecological and conservation importance.