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Sunday 18 November 2018

Comma a new addition to our butterfly fauna

The Comma is a recent addition to the butterfly fauna of Ireland
The Comma is a recent addition to the butterfly fauna of Ireland

Jim Hurley - Nature Trail

The spells of fine weather last week with warm sunshine, higher than normal temperatures and slack winds resulted in several butterflies being on the wing rather late in the season. The odd Small White, Red Admiral, Small Tortoiseshell and Speckled Wood was about and, surprise, surprise, I spotted a lone Comma looking like a tatty and raggedy Small Tortoiseshell but much brighter and more orange in colour.

The Comma is a new arrival to our shores. It is a strong flier and an insect of wide distribution; its range extends from north Africa to much of Europe and right across Asia to Japan. It is common in Britain and is steadily extending its range northwards into Scotland. In recent years it has colonised the Isle of Man and the island of Ireland. How it got here is unknown but there are two theories.

One theory is that a population eruption in Britain may have coincided with favourable easterly winds that carried the insects across the Irish Sea to our green and pleasant land. The second theory is the species may have arrived as eggs, caterpillars or pupae on plants imported from Britain.

However the frilly winged butterflies got here, they managed to survive and thrive. Distribution maps of the Comma in Ireland show that most reports are from the east coast of the country possibly supporting the theory that insects are being carried across the Irish Sea by easterly winds. There is no evidence that the Comma is a migrant.

When the butterfly closes its wings, the undersides are a mixture of dull browns save for a prominent white mark shaped like a comma; it is that mark that gives the insect its common English name.

Like our very common Small Tortoiseshells, Commas hibernate as adults. To tide them over the winter to need a high intake of sugar in autumn. As they approach the time for hibernation they range far and wide seeking out the last of the nectar-bearing late summer flowers, windfalls and rotting fruit. As a result, these woodland butterflies may well be seen in gardens at this time of year.

When adults hibernate, they close their wings. The mottled brown undersides and the jagged outline as a result of the scalloped edges of the wings give the impression of a withered leaf as the insect clings motionless to the trunk of a tree. The camouflage is obviously highly effective in making the butterfly inconspicuous to predators.

Sligo Champion

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