Butterflies a rare sight in April

IT’S quite unusual to see butterflies on the wing in April in this country but I’ve seen quite in recent weeks.

There was a small tortoiseshell, looking a bit dull and tattered. It was obviously an insect hatched last year that had been tempted out of hibernation by a spell of spring sunshine. But then I saw two red admirals and they were quite different — glowing with newly-minted colour.

I suspect some of the minor details of the life-cycle of the red admiral in Ireland remain to be discovered. They are usually described as migratory butterflies that arrive here from Morocco, with an intervening generation in Spain or France. But they certainly breed in Ireland and, according to JM Harding’s authoritative book Discovering Irish Butterflies: “it is possible that some over-winter here successfully”. So are red admirals in mid-April very early migrants or are they over-wintered specimens? The other butterfly in my garden the other day was an orange tip. This was less unusual because they are normally the first species on the wing every year. But this was a female and the males usually show up first. The female, of course, doesn’t have those bright orange tips to her fore-wings, she has black ones and she is slightly larger.

Some experts regard Irish orange tips as a separate sub-species. This is because on the upper surface of their wings the white parts have a faint dusting of yellow which is not found on orange tips in other countries.

Their preferred nectar plant is that pale mauve wild-flower that grows in damp places and is either called lady’s smock or cuckoo flower. It is also the preferred food plant of the caterpillar. It’s quite unusual for a butterfly to select the same plant species for nectaring and as larval food. However orange tips are not quite as strict as most butterflies when it comes to food for their caterpillars and females will lay eggs on garlic mustard and a few other related species if lady’s smock is in short supply.

Before depositing the egg the female inspects the plant very carefully to make sure there are no other eggs on it. This is important because caterpillars are cannibals. When they hatch out, provided there’s been no mistake and they don’t get eaten by another caterpillar, they start to feed on the seed pods of the plant. But after a week or two, even if there are plenty of seed pods left, they crawl down the plant and start eating its leaves. It then starts on the stalk.

Eventually the caterpillar suspends itself, with a silken thread at each end, from some piece of vegetation and pupates. The pupae over-winter and hatch into adults.