Comma

The latest of my 'nature notes' articles :-

Despite the rather cool and changeable weather we’ve had quite a bit of, I have managed to see a few butterflies around this spring - small tortoiseshells, peacocks, large whites (the gardener’s delight - not!), and spring specialities like the orange tip and the holly blue.  But I was delighted to see a bright and beautiful orange comma in our new garden, on a sunny day at the beginning of the month.

The comma has been described as “looking like a tatty small tortoiseshell”, as its wings have a jagged outline.  When at rest with its wings closed this provides good camouflage, as the undersides of the wings are dark, and the butterfly looks for all the world like an old withered leaf. The Comma is now a quite familiar sight across much of the UK, bucking the trend of butterfly decline by expanding its range. The butterfly carries a single white marking on its underside, which looks like a letter “c” (hence its Latin name of  Polygonia c-album) - or a comma.

This butterfly is one of several for which the stinging nettle is a larval food plant. The caterpillars do feed on other plants as well, including hops, and a decline in hop growing is thought to have been the reason for a sharp decline in comma numbers a century or so ago. The comma overwinters as an adult, and emerges quite early in spring if the weather is suitable. The male will establish a territory, often on the sunny edge of a patch of woodland (which exactly describes our garden). I observed “our” comma flying up and down and returning to settle on a chosen perch - typical behaviour. The caterpillars are black and white, and manage to look a lot like bird droppings.  As well as nettles and hops, they may feed on blackcurrant plants.

The adult butterfly is known in a number of forms, but there are two main types, one with a dark underside and one with a lighter underside (these are also brighter on the upper side).  The darker butterflies are normally the majority, and these appear by about the end of June or early July, to overwinter as adults.  The lighter coloured butterflies, however, go on to breed again almost straight away, to give a second generation of comma butterflies, appearing in August and September.  There will be more of these after a good and warm spring (so not this year, I should think!).

Butterfly life-cycles are often quite complicated; the trigger in this case seems to be day-length at the time the larvae are developing.  More of the lighter type of adult will be produced if at the time the larvae are developing the day length is still increasing. But a gloomier spring, and therefore a later start with the first brood, will mean that most of the offspring will not breed again, but will overwinter as adults.  Their darker coloration adapts them well for hiding in dusty corners or under bark.

Adult commas can be seen at any time of the year - even emerging on some warm winter days - but the main flying period is from April to the end of October.  Adults take the nectar of thistles, along with, for example, blackthorn in spring, ivy late in the season, and also fallen plums, blackberries and other fruit.