Nature Studies by Michael McCarthy: Such intoxicating displays of mimicry

Very occasionally a book comes along which enables you to see the world in a different way, and I have just discovered one. The title is Butterflies: Messages from Psyche and the author is Philip Howse, a retired Professor of Entomology at the University of Southampton. Published six weeks ago, the book is large-format, and since it is profusely illustrated with splendid photographs of butterflies and moths, many of them magnificent tropical species in bravura colours, your first thought is: coffee table. Yet something radical is going on in these pages which marks this volume out as one to be read rather than left lying around in your sitting room.

The title's a little confusing. It does not refer to psyche in the modern sense of the word as mind or spirit; it refers to Psyche, the lover of Cupid in Greek mythology, usually portrayed as a woman with butterfly wings, since in classical Greek "psyche" was the word for "butterfly". Simply put, the meaning of the title is that there are messages in the wings of lepidoptera which can be read, and this is immediately obvious in the cut-to-the-chase title of the American edition, to be published in August, which is Butterflies: Decoding Their Signs & Symbols.

Professor Howse's suggestion is that evolution has used the canvases of the wings of butterflies and moths to paint, in the wonderful colours we have always so admired, some very singular subjects. We have long known that these wings can play visual tricks, especially in terms of camouflage: two weeks ago on a Chiltern hillside a female brimstone butterfly with its wings closed was pointed out to me, perched in a buckthorn bush, and it so perfectly resembled one of the leaves that I was unable to pick it out until the pointing finger actually touched it. We also know that some species use warning colours to indicate to potential predators that they are poisonous: our marbled white is actually one of the browns, but looks like a chess board, and it was long suspected, and eventually proved, that its unusual colouration was a warning that it was toxic.

But Professor Howse is really concerned with mimicry. Many butterflies and moths mimic other species, especially in South America, where harmless species mimic the toxic ones with their warning colours, to get some free protection. In British butterflies, the most obvious piece of mimicry – at first glance – is the presence of eyespots on the wings of several species, the peacock above all, which has four. These are thought to suggest false "heads" where attacking birds will direct their first peck – thus allowing the insects a chance to escape.

But false heads of what? It is Professor Howse's novel and startling contention that heads and indeed bodies of a whole series of predators, from birds to foxes, from alligators to lizards, from spiders to snakes, are designed as images on butterfly and moth wings. Their purpose is to give an attacker a sudden shock, and he contends that this works because animals do not perceive and respond to objects or other creatures as whole images, but only to certain features of them. (This was famously first illustrated by the British ornithologist David Lack in his study of robins, where he showed that the birds were so primed to attack the red breast of a rival that they would even attack a bunch of red feathers brought onto their territory.) So a bird which sees a snake in a butterfly's wing will not think to itself, at least in the first instance, don't be silly, that's just a butterfly. It will think: Snake!

Under normal circumstances, says Professor Howse, we humans cannot see these images in the wings, because we are accustomed to seeing butterflies and moths in one standard way, set as dead specimens in a presentation case with their wings splayed out. But once we clear our minds of our preconceived views, he says, we can start to see them, and in the book's most striking aspect, he shows us. The picture of the snake on page 126 turns out on page 141 to be the wing-end of an Atlas moth from South-east Asia. The eyed hawk moth on pages 114-115 becomes, when seen upside down on page 117, the unmistakable representation of the head of a fox. The bottom of the hindwing of the purple emperor on page 163 is a perfect bird's head which I had never seen before, but now will never miss. There are countless such examples; and to me his theory is wholly convincing.

However, although a serious scientist himself, Professor Howse worries that his fellow scientists will not take it so seriously as he cannot back it up with experimental data; he cannot show – at least not yet –that creature X, confronted by an eyed hawk moth seen upside down, gives its fox alarm call. He should not worry. He is onto something new and remarkable. Have a look for yourself; it's the most fascinating butterfly book I've ever come across.

Summer punctuated by a surprise comma

On a more mundane butterfly note, I was sitting in the garden in the lovely weather of last weekend when a marmalade-orange leaf fluttered in and my daughter, who has just finished her A-levels, instantly exclaimed: "Look, Dad, a comma." And so it proved. I was filled with surprise and fatherly pride that the ardent young naturalist she was once, still survived. "I haven't forgotten it all," she laughed. And as we sat there, a holly blue flew in, and then a large white. And the buddleia's not even out for another fortnight.

m.mccarthy@independent.co.uk

For further reading

'Butterflies: Messages from Psyche', by Philip Howse (Papadakis Publisher, London, 2010) £25