Western Morning News (Saturday)
Butterflies preparing for winter
At this time of year, some butterflies are feeding up on sugary nectar and fallen fruit in readiness for hibernation in tree hollows, sheds and houses through the colder months, writes Charlie Elder
As autumn rolls in and temperatures gradually tumble, a few surprising guests can take up residence inside our garden sheds and homes. Tucked away in shady corners, some of our most beautiful butterflies seek refuge from the harsh winter weather ahead, their dark wings pressed together like dried leaves.
These are our hibernating species, which sit out the colder months in sheltered nooks and crannies, ready to get a head-start when spring finally comes around.
While most of our 59 breeding butterfly species spend the winter in the caterpillar stage of their life cycle, and others as pupae or eggs, a select few feed up on nectar and overwinter as adults, hidden in hollow trees, outbuildings and amid dense foliage.
Butterflies can increase their body temperature above ambient air temperatures by basking in sunshine or shivering their flight muscles, but in cold conditions they are forced to remain inactive. So winter is a time when they enter a dormant phase – though some may put in a welcome appearance on sunny or unseasonably warm days even in December and January.
The five butterfly species that hibernate are the brimstone, comma, red admiral, small tortoiseshell and peacock. The latter two regularly overwinter inside houses.
The brimstone tends to hide away among tangles of ivy or bramble in sheltered, sunny places. It is one of the first of our butterflies to emerge in spring and it is thought that the word ‘butterfly’ originally derives from descriptions of this butter-coloured species.
The well-camouflaged comma is secretive over winter and believed to lie low amid honeysuckle and hazel bushes. It is a handsome butterfly which could be confused with a fritillary or a small tortoiseshell, given that it has orangey upper-wings marked with bold blocks of dark patterning. Of the five hibernators it has the most ragged-edged wings, and the dark undersides are marked on the hind-wing with a white comma-shaped mark, from which it gets its name.
The other three species – red admiral, small tortoiseshell and peacock – opt for natural holes and hollows, but also favour man-made structures with a cool and constant temperature such as tunnels, garden sheds, barns and attics.
The red admiral, the most active of the overwintering butterflies, is resident in Britain year round, but the majority of those that we see in the summer are migrants from continental Europe, which breed here, adding to numbers – and it can be very common this month.
In appearance it has a distinctive contrasting combination of black and red and white markings on its upper-wings. The band of light red passes across the black fore-wing and around the rear of the hind wing, and it has blotches of white at the front of the wing-tips.
In the autumn red admirals can be seen feeding on fallen apples and other fruit, upping the sugar intake to maximise their reserves, and some may head south, while only a relatively small proportion survive our cold winters. The small tortoiseshell has marmalade orange wings, marked with black and gold blocks along the front and blue fringes around the rear edges. This garden regular can be early to bed come the autumn, and some will already be tucked up ready for winter – perhaps even flying in through an open window and settling high on a wall.
The peacock is arguably our most attractive butterfly, with symmetrical eye-spots on fore and hind wings,
designed to startle predators and highlighted with glittering touches of iridescent blue. When hibernating, with wings closed, it draws little attention to itself, having dark brown underwings like the two other fellow species which hibernate in natural cavities and buildings.
The peacock, red admiral, small tortoiseshell and comma butterflies belong to a grouping affectionately known as the ‘aristocrats’, which includes among its number the painted lady. This fast-flying wanderer is a summer migrant from countries further south, spreading and multiplying in favourable conditions.
The painted lady, which has black and white markings on a pinkish-orange background, can be seen in the UK in spring and summer, and some may even head back south in autumn. However, they are unable to survive our colder months – although they have been recorded overwintering in Cornwall.
If you see a painted lady butterfly in winter – and an individual surprised me in my Dartmoor garden one February morning a couple of years ago – then this is probably one that has flown here out of the blue on warm winds from the south.
Butterflies such as the small tortoiseshell and peacock which end up hibernating in our homes can run into problems once the central heating is turned on. They can desiccate or become active with no ready source of food.
Simply letting them go outside in harsh winter conditions spells a death sentence, so the advice is to relocate them to a suitable setting – such as a garden shed.
Richard Fox, of the charity Butterfly Conservation, writes on the charity website: “How best to help these poor confused butterflies unwittingly tricked into thinking spring has come early? The best solution is to rehouse them into a suitable location. Catch the butterfly carefully and place it into a cardboard box or similar, in a cool place for half an hour or so to see if it will calm down.
“Once calmed down you might be able to gently encourage the sleepy creature out onto the wall or ceiling of an unheated room or building such as a shed, porch, garage or outhouse. Just remember that they will need to be able to escape when awakening in early spring.
“If you have no options at all for suitable hibernation places, then it would be best to keep the butterfly as cool as possible, to minimise activity, and then to release it outside during a spell of nice weather.”
A butterfly in winter is always a special sight, so keep your eyes peeled over the months to come for our regular hibernators, resting up in sheds, stable blocks, outbuildings, barns and loft spaces. Those that make it through will be the first to bring a splash of colour to our gardens come the spring.