Winter's Sleeping Beauties
In the cold, grey weather of winter a splash of glorious Technicolor is conspicuous by its absence: the butterfly. Many have simply died, and a new brood waits to be reborn, but others choose a solution more readily associated with mammals…
The eye-catching Peacock butterfly
The beautiful Peacock and Small Tortoiseshell butterflies that you have until very recently seen feeding on Michelmas Daisies in your autumn gardens are the same butterflies that will be out and about searching for flowers on the first sunny, warm day of the new year. Not the same type, exactly the same individuals.
How? They hibernate over the long winter months, putting their bodies in a form of stasis in a similar way to hedgehogs, dormice, and countless other mammals.
Most other butterflies have different methods of coping with winter. A few migrate to warmer climes where nectar is available, but most survive the winter in the inactive egg or chrysalis stage, or hibernate as a caterpillar. But there are a handful of butterflies in this country which slumber until the warm weather returns. These butterflies live for about nine months in their adult stage, and much of this time spent in hibernating sleep. Many people do not realise that any butterfly is capable of hibernation, something which is more associated with mammals than insects.
The Peacock and Small Tortoiseshell are usually up and about in March, while the Brimstone, which favours the flowers of the woodland rides, can often be seen much earlier, particularly in the south of England – even in January if the weather is suitable.
In late autumn the Peacocks, Small Tortoiseshells and Brimstones search for a safe, dry, dark place where they will be protected from winter frosts – they will often venture into people’s houses.
Usually Peacocks find a hollow tree, although they will sometimes tuck themselves in a woodpile or a corner of a garden shed.
Small Tortoiseshells choose similar places, but are also quite likely to come
indoors. A hideaway behind a picture in a little-used room is safer than a hollow tree: there are no birds to eat them while they sleep.
Brimstones seek dense evergreen cover in their woodland surroundings – and particularly thick growths of ivy or holly which offer protection.
The butterflies often bury themselves among dead leaves. At rest, the bright wing colours are hidden; only the underside, looking like a dead leaf, is visible. This gives the butterflies particularly good camouflage.
The Peacock has a spectacular defence mechanism which it uses if it is disturbed from rest. Opening its wings, its creates an alarming hissing noise as the front and hind wings rub across each other, revealing huge ‘eye spots’. A small bird startled by the hiss and then confronted with large owl-like eyes will usually fly off, leaving the butterfly to go back to sleep.
Butterflies need the sweet energy-rich nectar from flowers to give them strength to fly and help them survive their hibernation through the long winter months. During this inactive stage their energy consumption is minimal so they can survive without further food. As protection against the cold, some sugar in their blood is converted to glycerol which works rather like antifreeze in car radiators.
When the first spring sunshine in late March the Peacocks and Tortoishells awake from their hibernation; individual Peacocks can be seen much earlier in fine weather, when they come out for a short flight. Although the Brimstones may be tempted to stir as early as January, they return to hibernating until later.
Sometimes Tortoiseshells hibernating indoors also wake too early, perhaps because the heating is switched on in the spare room. Whatever the reason, if
you see a Tortoiseshell fluttering at a window in midwinter, you should put it in a cool shed or garage where it can go back to sleep until spring arrives.
It should be noted that in addition to the hibernating population of Small Tortoiseshells, this country's population is also augmented by a small number of migrants arriving each spring.
Brimstones which emerged at the start of the year lay their eggs. By July and August their new brood of adult Brimstones emerge, having quickly gone through the egg, caterpillar and chrysalis stages to become butterflies. These new adults spend most of the day feeding. They show distinct preference for purple flowers, particularly those of knapweed, scabious, bramble and clover, full of nectar to not only keep them flying now, but build them up for hiberntion..
Meanwhile, the new brood of adult Tortoishells, which emerge in late June and July, lays eggs to produce a second brood in August and September. This feeds on most garden flowers, especially ice plant and buddleia, and is the overwintering brood.
The new Peacocks emerge later – in August – and are numerous in gardens where they feed on buddleia, and in fields where they enjoy lucerne, thistle, knapweed, marjoram and clover.
If you want to attract these, or any, butterflies to your garden, it's easy - but you will need more than flowers than just flowers alone. A patch of nettles in a sunny corner of the garden will feed the caterpillars which will turn into chrysalis and eventually become the next generation of butterflies. And an undisturbed corner of a shed will give the butterflies somewhere safe to hibernate. These measure will ensure our Skeeping Beauties continue for generations to come – without the help of a handsome prince…
The underside of this Peacock looks just like a dead leaf, giving it excellent camouflage should it choose to hibernate amongst a fallen pile.
The slightly ragged and faded appearance of this Small Tortoiseshell is the giveaway of its age. It has survived winter hibernation and will go on to mate and lay eggs before dying.