Dear Readers, one of the commonest and most familiar of the butterflies in our gardens at this time of year is the Red Admiral (Vanessa atalanta). While I was staying with my parents in Dorset this week I found a number of them visiting the buddleia bush, and was surprised both at how confiding they were, allowing me to get within a few inches of them, and how tattered and worn they looked. Some had so much wing damage that I was surprised that they could fly at all.

It isn’t surprising that these creatures look a little tired – most of them have made a migration all the way from central Europe to the UK to breed. Recently, however, some Red Admirals are hibernating in our garages and sheds, and the milder British winters mean that they can survive, making them a rare beneficiary of climate change. They are now officially a native species, after all their long history of presence in this country. In the autumn, some butterflies will make the journey in reverse, and have been spotted gathering over the White Cliffs of Dover just like migratory birds. In spite of their fragile appearance, these are tough, determined insects.

On arriving in the UK, a female Red Admiral will waste no time in finding a patch of nettles and depositing a single green egg at the growing tip of each one. They look a little like sea gooseberries to me, perfect and delicate, and will hatch after about a week.

As the caterpillar emerges, it wraps the leaf around itself as protection – you will often find whole patches of nettles with these little caterpillar cigarillos. They will enlarge the parcels each time they shed their skin, which is usually five times. The mouths of the newly-emerged young are so small that they can’t eat right through the leaf, just scraping away the outer layer. But as they grow, they become more voracious, cutting perfect half-circles through the edge of the leaf with each toss of their heads. Caterpillars are basically eating machines: while their preferred food plant is stinging nettle, they will sometimes munch through hops and pellitory of the wall. The caterpillars of the Red Admiral are spikey little black things, completely different to their elegant parents.

Once the caterpillar has reached the requisite size, after about four weeks, it will start to pupate. This is a process that has bewitched human beings ever since they realised that the lumpy, earthbound larva becomes a butterfly. It is extraordinary to me that all the material required for the transformation exists not only in the body of the caterpillar but in the egg itself. The germ of everything that is needed to make wings and antennae and compound eyes is already there. The one part of the caterpillar that remains relatively unaltered during the process are those six little legs at the front that turn into the long elegant legs of the butterfly. Everything else seems to be utterly changed.

When a caterpillar is ready to pupate, it stops eating. It draws together several leaves to make a silk tent, and then spins a silk holdfast for itself, called a cremaster. And then, the skin splits, and something new emerges, and dries. Where there was frantic movement, there is a pregnant stillness. The pupa is beautifully camouflaged, easy to overlook. But inside, something new is happening, and after two to three weeks, the adult emerges.

The Red Admiral is not a rare butterfly, but it is a very fine one, in its livery of chocolate brown and vermillion. There is much debate as to whether the ‘Admiral’ is a corruption of ‘admirable’, or a reference to the ensign flown on ships when the admiral was aboard. In France, however,  it is known as ‘le vulcain’, after the blacksmith of the gods. Its appearance in many European paintings may indicate temptation, with the crimson and smoky-grey wings being seen as reminiscent of the fires of hell. What a weight of symbolism for a butterfly to bear! And sometimes it might have led to the butterfly’s destruction, as there are old stories of a ‘red butterfly’ that was hunted in the north of England and the Borders as a witch.

In truth, of course, the Red Admiral is a harmless creature and attractive creature, with no demonic intentions that I can detect. As an adult, the Red Admiral seems to have a liking for buddleia and thistles in particular, and is one of the last butterflies to still be on the wing in autumn – it is often seen feeding on windfall plums and apples. I have a great fondness for the damaged, faded creatures that are currently on the wing. They’ve probably crossed mountain meadows and fluttered across twenty-six miles of salt-water. They’ve maybe survived the attentions of birds and dragonflies, and have lost their bright-painted colours on the way. But by now, they have probably reproduced, and will soon be joined by their splendid, new-minted, perfect offspring. Who could begrudge these elderly insects their pleasure in nectar, or in basking in the sun?

Sources this week include Bugs Britannica by Peter Marren and Richard Mabey, and The Butterfly Isles by Patrick Barkham, both full of fascinating information.