Read an Excerpt
Rainbow Dust
Three Centuries of Butterfly Delight
By Peter Marren The University of Chicago Press
Copyright © 2016 Peter Marren
All rights reserved.
ISBN: 978-0-226-39591-3
CHAPTER 1
Meeting the Butterfly
Everybody knows what a butterfly is. They are the most colourful of insects, the ones with painting in their wings. The butterfly flies in the sunshine and visits flowers and, at least in the eyes of the poet, lives a short but joyous and carefree life. They charm and delight us and make us think well of nature. It is their beautiful colours that might have inspired the name 'butter-fly' and that certainly underlie their individual names. In Britain we have Common Blues and Green-veined Whites, Clouded Yellows and Wall Browns. Those with many colours or more complicated patterns we accord names like tortoiseshells, peacocks and fritillaries. We award high rank to some: admirals, monarchs, emperors.
Butterflies are a self-contained group of insects, a distinctive class within the order Lepidoptera ('scaly-wings') which also contains the much more numerous moths. It ought to be easy to say what a butterfly is and how it differs from a moth. But a scientific definition of a butterfly is less clear-cut. Yes, they fly by day, but so do a great many moths. Yes, they are colourful but have you ever seen a tiger-moth? Yes, most butterflies do not resemble your average moth but the small butterflies called skippers are very moth-like. Some moths have stout, hairy bodies but others are more slender and butterfly-like.
The one sure way to tell a butterfly from a moth is to look at their antennae. These are used to detect scents in the air, such as the delicate pheromone of a mate or the chemical signature of a favourite flower. All butterflies have little clubs at the end of their antennae. Moth antennae, on the other hand, can be feathered, or like wires, but are never clubbed – though, just to be awkward, the day-flying burnet moths have antennae that thicken towards the ends. There are other technical differences such as the way the wings are constructed. Most moths possess a little hook and attachment that links the wings and enables them to buzz like bees. Butterflies do not have that option; instead, and, again, with the usual exception of the skippers, they beat their wings or, in some cases, glide between wingbeats. Butterflies 'flutter by'. Moths buzz off.
The simplest way to tell a butterfly from a moth is to get to know the butterflies. There are only fifty-nine resident species in Britain, plus eight rare migrants and three extinct species, compared with nearly a thousand larger moths alone (and still more tiny ones). Butterflies that visit gardens are even fewer – perhaps twenty. Nearly all of our species are easy to recognise and they all have English names. And when it comes to identification we are spoiled for choice. It would be hard to find any bookseller without at least a couple of butterfly books. Even guides to insects in general routinely include all, or nearly all, the butterflies. There are also numerous sites online, as well as gizmos such as CD-Roms that picture them all and point out the differences.
Every species of butterfly has its own lifestyle. Some live mainly in woods, others in grassland or moorland or along the coast. Some, generally those with a powerful flight, roam from place to place while others tend to stay put, close to the bush or patch of flowers where they came into the world. What they all share is a life cycle that involves a series of transformations. The female butterfly lays an egg which hatches into a tiny caterpillar. A caterpillar has only one biological task: it must eat and carry on eating until it reaches full size, and as rapidly as possible. Caterpillars are plant eaters, though the exact plant they eat differs from species to species. Peacocks and Red Admirals feed on stinging nettles. Many fritillary caterpillars graze on violet leaves. Most of the browns and skippers feed on wild grasses. Being of only limited flexibility, caterpillars have to pause and change their skin every now and then as they fatten up. In the final skin change, they change form completely and turn into the dormant phase known as a pupa or chrysalis. Inside the apparently sleeping chrysalis a rearrangement takes place that eventually produces the adult butterfly. A day or two before the butterfly is fully formed, the chrysalis darkens and wing colours show faintly beneath the skin. Finally, when all is ready, the chrysalis splits open and, in one of those moments in nature that we find so miraculous, the butterfly pops its head out and sees and smells the world for the first time.
Anyone who has reared butterflies will know that moment. Caterpillars have limited value as pets. They show no emotions at all, let alone evident happiness or gratitude as you supply them, over and over, with fresh leaves. They simply chew plant tissue at one end and void it at the other in little brown pellets known as frass. Wherever possible I used to pot some plants or cover a branch with muslin, drop in the caterpillars and forget about them. Admittedly not all caterpillars are dull; many are adorned with pretty spikes or horns, or attractive colours, and the Puss Moth caterpillar even has a pair of little tails. And there is something hypnotic about watching a big caterpillar – a hawkmoth, say – quickly reduce a leaf to a bare stalk. But on the whole it is a relief, not to say an end to anxiety, when it finally reaches full size, spins a pad of silk, hunches and seems to shrink into itself and duly turns into a pupa or chrysalis.
The emergence of the butterfly is something else. I see it in my mind's eye now, that moment when the sleeping chrysalis seems to wake up, wriggle and kick, and suddenly split along the groove where the wings show through. The thing inside, not yet recognisable as a butterfly, puts out its head. It unfurls two long antennae from a pouch just below the skin of the chrysalis and, flickering like a snake, tries out its coiled tongue. Quickly, almost too quickly to take it all in, the thing wriggles out, using its new-born feet to grip the old skin and drag the rest of its body out of its shell. Attached to its chest, just above the legs, are four pulpy, coloured flaps. The thing reverses itself and, now facing up instead of down, and gripping the shell of the chrysalis, it sets about creating and drying its butterfly wings. Its body bulges and squeezes as fluid is pumped down the veins to the edges of the wings. Ever so slowly they unfurl and expand. It might take an hour and in every minute the thing becomes more and more recognisable. Then, in a moment of glorious apotheosis it opens its pristine, gorgeous wings for the first time and turns into a butterfly. Any excess fluid, which can be transparent but in some species is blood-red, is voided. And then, after a couple of practice beats of its splendid wings, the butterfly leaves its old body behind and launches out into the air and begins its brief adult life.
How brief is that? Butterflies live longer than mayflies but not as long as bees. For those that do not perish prematurely, in a spider's web or as bird food, their adult life may last a week or two. The colours and patterns of a butterfly's wing are formed by tiny overlapping scales. The silky sheen of a newly emerged butterfly is lost within a day or two, and, as more and more of the scales are rubbed or shed it becomes increasingly worn and faded. The wings also become ripped and tattered from rain and thorns or take on triangular tears from bird attacks. The longest-lived butterflies are those that pass the winter as adults, in hibernation. Such are the Small Tortoiseshell and the Peacock, which often seek refuge in garden sheds, and the Brimstone which prefers to over winter in a dense knot of ivy. Those species can live several months, though, of course, they are inactive and 'asleep' half the time. If you add up the time they spend as an egg, caterpillar and chrysalis, single-brooded butterflies, such as the Purple Emperor or the Chalkhill Blue, live a full year. Those which have more than one generation, like the Adonis Blue, which appears in May and again in August, have shorter cycles. A full summer cycle from egg to egg-laying butterfly takes about three months.
How does a butterfly spend its life? I once helped to supervise the work of a student who did her best to follow one species, the smallest of all our butterflies – the Small Blue – from the day it emerged from the chrysalis until the day it died. A large part of this butterfly's life was spent immobile on a grass stalk ('sleeping'), warming up in the sun (sunbathing) or gorging on the nectar of vetch flowers. Butterflies taste with their feet. It might sound odd but this gives them a much more sensitive palate than the human tongue. Like many butterflies, this feisty little blue established a home range or territory. It saw off rivals which it detected by sight and found a mate which it discovered by using its sensitive antennae. The mating ritual of a butterfly is unhurried. The male displays its wings, might waft an attractive scent towards its partner with its wings and generally does its best to impress. The female might offer herself or she might not. If the former the couple stay paired for an hour or more. There is no hurry.
It all sounded like a pretty good life to me (though with the danger of sudden death at any moment) and I felt almost envious of the Small Blue. The female of the species, which in butterflies is often less brightly coloured, has the tougher role. She has the burden of scores of thick-shelled eggs to carry and the chore of finding places to lay them. In the case of the Small Blue, the butterfly uses its senses to find a suitable patch of kidney vetch – its yellow blossoms are the small Blue caterpillar's only 'food plant' – that is, one not already discovered by a rival Small Blue. The competition must be intense. Each time she has to deposit a single blue-white egg in exactly the right place, on the hairy calyx leaf underneath the flower. This involves abdominal straining as the butterfly does its best to glue the egg into a hiding place while clinging on to the awkwardly shaped flower. At the end of her mission she must be exhausted. On the whole I would rather be a male Small Blue – fucks, fights and scented delights! – even though they have an unfortunate appetite for dog shit.
Butterflies feed on liquids using a long tubular proboscis, a kind of flexible straw. Their standard diet is sugar-rich nectar from flowers – and they incidentally pollinate the flowers in the process. Some species are also attracted to 'honeydew' left by aphids, to salt-rich water oozing from seepages in the bare earth, the juices from overripe fruit, sap escaping from a wounded tree or fresh mammal droppings. In very hot weather butterflies can even be attracted to sweat. Needless to say, they need a plentiful supply of the right kind of flowers. The one way humankind can help them is to provide suitable flowers in our gardens, such as mint, lavender, wallflowers, red valerian and, of course, the 'butterfly bush', buddleia. It is easy to design a butterfly garden: just plant the right species in a sunny location. There is no need to plant stinging nettles. There are plenty of them around already.
Butterflies face many hazards: parasites, disease, predators, plus our own contribution of insecticides and habitat destruction. The chances of any one egg making it through to an adult butterfly are small. That is why butterflies lay a lot of eggs (by the same token, stealing a butterfly's egg does not have the same impact as stealing a bird's egg). Britain offers a further problem in that we have a cool, wet, uncertain climate. Butterflies thrive on sunshine and certainty. Unlike mammals, they have no internal heating system. Their body heat is generated externally by basking and using their wings to regulate the temperature. A spell of cold weather results in more caterpillars becoming casualties and so fewer butterflies on the wing, and therefore fewer eggs being laid. Bad summers are very bad for butterflies. Fortunately they have the capacity to recover quickly in warm years (otherwise we would probably have no butterflies at all).
Like birds, some butterflies migrate (though, unlike birds, that fact was not appreciated properly until well into the twentieth century). Among our common migrants, the ones that arrive every year, and sometimes in large numbers, are the Red Admiral, Painted Lady and Clouded Yellow. We also have several more occasional migrants such as the Camberwell Beauty and the Monarch. To fly long distances over land and sea takes strong wings and tough flight muscles. You can see it at work when you encounter a Painted Lady on its way north. These butterflies do not flutter by; they fly straight and fast, as though they know where they are going (each has, in fact, no idea where it is heading, but its genes do). Butterflies are short-lived and few, if any, of those that reach us in the spring will survive to attempt the return journey to southern Europe or North Africa. It is the second, British-born generation that makes the return journey. You can see migrant butterflies as conveyors of genetic material, taking their genes north for the summer and then, in a different body and generation, back home again. But even when the facts are familiar and the process broadly understood, it still seems incredible that anything as fragile as a paper-winged butterfly can endure weeks of flight, using the sun as a compass, high above the curvature of the earth.
Migration is not the only butterfly mystery still being unravelled. Another is how dependent many of them are on other species, particularly ants. Ants are aggressive predators which live in underground nests in very large numbers. Make friends with an ant and you have a protector for life. The dependence of one of our rarest butterflies, the Large Blue, on a particular kind of ant has been well known for a century. Here the protection is rather lopsided since the butterfly's caterpillar helps itself to the ant's grubs as a midwinter larder (helped, it was found later, by smelling like an ant and even 'singing' like one). But other blues and hairstreaks, too, depend on the protection of ants. Their caterpillars and chrysalids produce secretions that attract ants and ensure they become well-attended by ant escorts. One of the most amazing sights of the butterfly world, one discovered only recently, is the emergence from the ant's nest of a Silver-studded Blue butterfly with anything up to eight ants frantically licking its body. The hour which every butterfly has to spend drying its wings is perhaps the most vulnerable of its whole life. But with a posse of fierce ants to stand guard, the chances of survival are much greater.
Insights like this take many years of patient research and observation. Butterflies are amazing. Nature is amazing. But anyone can get a front seat on the drama of butterfly lives, simply by rearing them. I used to do that. I used to collect them too. I'll explain how and why in the next chapter.
CHAPTER 2
Chasing the Clouded Yellow
'I haven't seen a single butterfly collector in the past twenty-five years', said Matthew Oates. We were staring up at the treetops hoping to spot a Purple Emperor. Purple Emperor butterflies spend most of their lives up in the sunlit canopy of English woods, descending only to drink from puddles or to imbibe some life-enhancing substance from dog shit or roadkill. Unless you are in luck, you need binoculars to get a good view of the dark butterflies forty feet overhead. Emperor-watching is like bird watching: a matter of glimpses punctuated by the occasional freeze-frame as the glorious purple-shot butterfly alights on a leaf to bask or sip the sticky honeydew secreted by incontinent aphids.
Matthew is our most experienced observer of the Purple Emperor, once the greatest prize of any collector. And if Matthew hasn't seen a single person trying to catch his beloved Emperors in a full quarter-century then they are either very good at hiding or, more likely, no one is trying to catch them any more.
Like Matthew, I cannot remember when I last witnessed anyone collecting British butterflies. But I am old enough to remember when it was still one of the classic hobbies of a young naturalist, along with other kinds of collecting – fossils, pebbles, feathers, pressed flowers, shells. Those hobbyists included me; I too was for a while addicted to catching butterflies. Back then, in the 1950s and early 1960s, almost every butterfly book offered tips on how to form your own collection and how to breed up more butterflies from eggs and caterpillars. In fact it was hard to imagine anyone being seriously interested in butterflies without collecting them.
It was maybe ten years after that when attitudes began to change and collecting was no longer respectable. It wasn't through any change in the law. A few species of butterflies and moths were legally protected for the first time in the 1970s but the intention behind the protection was educational. It drew attention to the plight of certain rare and attractive species that could, in theory, become endangered by over-collecting – but offered no evidence that anyone was actually collecting them. Perhaps the demise of the butterfly collector had more to do with improved camera technology and faster colour film which made it much easier than before to obtain good, sharp images of live butterflies. It was also, of course, connected with a dawning realisation that we were trashing the countryside and its wildlife. Butterflies were becoming less common, not because of collecting but as a result of their habitats being ploughed or drained away or turned into roads and suburbs. The same kinds of people who collected butterflies two or three generations ago became equally ardent conservationists. They stopped collecting butterflies and joined a recording scheme instead, or acted as volunteer wardens on their local nature reserve. Conservation was in and collecting was out. Quite suddenly, and without much fuss or argument, it had become socially unacceptable, and that was that.
(Continues...)
Excerpted from Rainbow Dust by Peter Marren. Copyright © 2016 Peter Marren. Excerpted by permission of The University of Chicago Press.
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