Common Blue is a rare beauty

ENCOUNTERS with butterflies are among the highlights of an Irish summer.

The number of species in this country is small compared to other parts of Europe but includes truly spectacular insects. The list of species in Ireland is growing. Some new ones are colonising us from abroad; some have been here all the time, unrecognised because they’re similar to other species.

The Comma (above) is a butterfly colonising the country from Britain, and Real’s Wood White, the Essex Skipper and the Small Skipper were unrecognised until recently.

But the Irish list, including migrants and rarities, is only 35 species. This makes the study of butterflies ideal for amateur naturalists, because such a small species list can be mastered quickly. Which of these 35 butterflies is the most beautiful is a difficult question. But I wouldn’t go for one of the large and garish species, like a Red Admiral or a Peacock. I’d go for one of the Blues.

There are three species of Blue butterfly breeding in Ireland. The Small Blue is tiny, its wingspan only 16 to 25mm, and it’s the least colourful of the three. The undersides of the wings are grey and the upper surfaces smoky brown, though males have a faint dusting of dark blue scales. There are a few inland records from quarries, sand-pits and part of the Burren, but it’s largely confined to coastal sand dunes with kidney vetch, the larval food plant. It’s rare, and declining as a result of an increase in links golf courses.

The holly blue is increasing in numbers and spreading rapidly. It’s a thumb-nail sized butterfly with deep lilac-coloured wings with black tips, which are more pronounced in the females. They have two or even three broods in a year, the caterpillars of the early broods feeding on holly and those of the later ones on ivy.

But it’s the third species, the Common Blue (above), which I submit is the beauty queen of Irish butterflies. The common blue has become uncommon, though it’s widely distributed on unimproved grassland containing bird’s foot trefoil, the yellow-flowered plant the caterpillars feed on. Its glory is in its colour. Males are a brilliant sky blue with a narrow white border to the wings, which is stippled with tiny black spots. In Ireland, females are blue as well, with orange spots just inside the white wing border. We have our own sub-species of the common blue, called ‘mariscolore’. In Britain, the males are smaller and less intense in colour. British females have brown wings. The British type occurs in Ireland, mainly in eastern coastal counties.

The first butterflies hatch out from over-wintered caterpillars in May. They mate and the female alights on a trefoil plant, testing it by ‘drumming’ on the leaves and flowers with her front legs and bending her antennae to taste and smell it. When she’s satisfied, she slowly deposits her eggs, one by one, onto the plant. These eggs will have become adult butterflies by now and these may be on the wing, and producing more eggs and caterpillars, up until October if it’s a mild autumn.

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