A welcome population explosion

IN his column last week, Damien Enright celebrated the butterflies.

Where he lives, cabbage-whites and speckled-woods predominate. In the fields along the coast of north Co Dublin, there are also lots of butterflies but most of them are tortoiseshells. I have never seen so many as we have at present. Our Irish species is the small tortoiseshell, with a wing-span of 4 to 5cm. A bigger cousin, the large tortoiseshell, is found in mainland Europe and occasionally in Britain.

The small tortoiseshell’s colourful markings are immediately recognisable; a glorious design of red, yellow and white patches against a dark background. A row of bright blue dots runs along the insect’s rear fringe from wingtip to wingtip. The undersides of the wings are dark; when they are closed and held vertically above the torso, the insect is well camouflaged. Butterflies, however, can’t afford to hold this posture for long. They must open their wings to receive the sun’s bounty, an activity known as “basking”.