What’s the best way to survive winter? Ask a butterfly, because they know better than most

Our Environment Editor, who has published at length on these beautiful creatures, reflects on their life cycle. Plus: a festival of fieldfares

A A A

Earlier this week, Nasa issued a satellite photo of a stark  white Britain plastered in ice and snow, and I thought to myself it looked striking, but lifeless. It’s easy to have the same feeling sometimes at ground level, gazing on a snowbound countryside: it has become a barren white desert. Which, of course, is mistaken entirely.

Under the frozen blanket, life is abounding but sleeping: the seeds of a thousand plant species are just waiting for the sun to knock on their door; insects are in the same position. But whereas seeds are seeds, insects – let’s take butterflies – can have very different identities under the snow.

The great wonder of butterflies, of course – the attribute which has charmed children down the centuries – is metamorphosis: keep a caterpillar in your bedroom and eventually it will turn into something sensational.

In all, butterflies have four stages in their life cycle: egg, caterpillar, pupa or chrysalis, and adult. And an aspect of this which has long fascinated me is that different butterfly species overwinter using all four of these forms.

I wrote about it here last year. Of Britain’s 58 types of butterfly, nine spend the winter as an egg; 32 spend it as a caterpillar; 11 go through the cold times as a chrysalis; and six winter as fully grown adults.

All the 11 browns, for example, from the meadow brown to the gatekeeper, overwinter as caterpillars, whereas each of the five whites, from the large white to the green-veined white, winters as a chrysalis, and the three well-known, related and very colourful species – the small tortoiseshell, the peacock and the comma – all spend the winter as fully grown adults, often hiding in houses and garden sheds.

What I had never asked myself until recently, though, was why different species choose such radically different strategies. It won’t be random. There must be a reason. I tend to believe that, with evolution, there’s a reason for everything (just don’t ask me what my nipples are for, OK?).

What I supposed was that it would represent different ways of coping with the cold; this one is warmer as egg, that one as a pupa. But hankering after the truth, I rang up the man who knows more about butterflies than anyone else in Britain, Jeremy Thomas, Professor of Ecology at Oxford (he who brought the large blue back from extinction, and wrote the best book on British butterflies ever published).

Jeremy quickly disabused me of my ignorance: the strategy you use to overwinter as a butterfly, he explained, allows you to synchronise your emergence as a caterpillar the next year with the availability of your food plant. It’s not about keeping warm: it’s about timing.

Most caterpillars are entirely dependent on a very small range of plants, or just a single one; and so the caterpillar has to start feeding when the plant is available, or at its best. It also has to avoid competition.

Jeremy gave me a vivid example in the case of two blue butterflies, the chalkhill blue and the Adonis blue, among our loveliest insects of high summer, the first a milky pale blue – like a sky with thin, high clouds – the second the dazzling iridescent blue of the sea in full sun. They are closely related; but whereas the chalkhill blue overwinters as an egg, the Adonis blue does so as a caterpillar.

The reason is that they share the same food plant on the chalk downland where they are found, horseshoe vetch; and if both began feeding on it at the same time, there might not be enough to go around. So the Adonis, already a caterpillar when the winter ends, has a head start; whereas the chalkhill, as an egg, has to catch up, and comes out as a caterpillar about six weeks later, so it is not in direct feeding competition with its cousin, which by then has become a chrysalis.

I shall look at them with even more interest in future, although just picturing them in my mind’s eye now, at the advent of February, is enough to lift the spirits.

A festival of fieldfares

Last week, I wrote about that boisterous, colourful, winter thrush from Scandinavia, the fieldfare, coming into my south-west London suburban garden for the first time to feed on berries, because of the hard winter; 21 people from all over the country have since emailed me with details of the same thing happening to them. I’m glad I’m not alone in enjoying one of the best compensations for a Big Freeze.

PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Service and Installation Engineer

£22000 - £28000 per annum: Recruitment Genius: A fantastic opportunity has ari...

Recruitment Genius: SEO / Outreach Executive

£20000 - £23000 per annum: Recruitment Genius: Our client is a global marketin...

Recruitment Genius: Junior Estimator

£17000 - £18000 per annum: Recruitment Genius: A fantastic opportunity has ari...

Recruitment Genius: Sales Negotiator - OTE £24,000

£22000 - £24000 per annum: Recruitment Genius: An enthusiastic individual is r...

Day In a Page

A timely reminder of the bloody anniversary we all forgot

A timely reminder of the bloody anniversary we all forgot

Who remembers that this week we enter the 150th anniversary year of the end of the American Civil War, asks Robert Fisk
Homeless Veterans appeal: Former soldiers pay their respects to a friend who also served

Homeless Veterans appeal

Former soldiers pay their respects to a friend who also served
Downfall of Dustin 'Screech' Diamond, the 'Saved By The Bell' star charged with bar stabbing

Scarred by the bell

The downfall of the TV star charged with bar stabbing
Why 2014 was a year of technological let-downs

Why 2014 was a year of technological let-downs

Security breaches and overhyped start-ups dominated a year in which very little changed (save the size of your phone)
Cuba's golf revolution: But will the revolutionary nation take 'bourgeois' game to its heart?

Will revolutionary Cuba take 'bourgeois' golf to its heart?

Fidel Castro ridiculed the game – but now investment in leisure resort projects is welcome
The Locked Room Mysteries: As a new collection of the genre’s best is published, its editor Otto Penzler explains the rules of engagement

The Locked Room Mysteries

As a new collection of the genre’s best is published, its editor explains the rules of engagement
Amy Adams on playing painter Margaret Keane in Tim Burton's Big Eyes

How I made myself Keane

Amy Adams hadn’t wanted to take the role of artist Margaret Keane, because she’d had enough of playing victims. But then she had a daughter, and saw the painter in a new light
Ed Richards: Parting view of Ofcom chief. . . we hate jokes on the disabled

Parting view of Ofcom chief... we hate jokes on the disabled

Bad language once got TV viewers irate, inciting calls to broadcasting switchboards. But now there is a worse offender, says retiring head of the media watchdog, Ed Richards
A look back at fashion in 2014: Wear in review

Wear in review

A look back at fashion in 2014
Ian Herbert: My 10 hopes for sport in 2015. Might just one of them happen?

Ian Herbert: My 10 hopes for sport in 2015

Might just one of them happen?
War with Isis: The West needs more than a White Knight

The West needs more than a White Knight

Despite billions spent on weapons, the US has not been able to counter Isis's gruesome tactics, says Patrick Cockburn
Return to Helmand: Private Davey Graham recalls the day he was shot by the Taliban

'The day I was shot by the Taliban'

Private Davey Graham was shot five times during an ambush in 2007 - it was the first, controversial photograph to show the dangers our soldiers faced in Helmand province
Revealed: the best and worst airlines for delays

Revealed: the best and worst airlines for delays

Many flyers are failing to claim compensation to which they are entitled, a new survey has found
The stories that defined 2014: From the Scottish independence referendum to the Ice Bucket Challenge, our writers voice their opinions

The stories that defined 2014

From the Scottish independence referendum to the Ice Bucket Challenge, our writers voice their opinions
Stoke-on-Trent becomes first British city to be classified as 'disaster resilient' by the United Nations

Disaster looming? Now you know where to head...

Which British city has become the first to be awarded special 'resilience' status by the UN?