Having a flutter: a lack of food for butterfly larvae has eaten into numbers. Photo: Getty
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Butterflies are beautiful but we need to love their larvae too

The numbers of monarch butterflies are at a record low and a large part of this is because of the disappearance of the milkweed plant, eaten by caterpillars.

Sometimes, to prove a point, you have to starve a larva. It’s all too easy to be bewitched by the beauty of a passing butterfly but not so easy to admire the foraging of a voracious caterpillar. We should, though: it turns out that the two are linked.

Researchers in the US have been putting monarch butterfly larvae on strict diets and observing the consequences for the butterflies they become. This kind of butterfly is in grave trouble. Every year, the insects perform an extraordinary 3,000-mile migration from Canada and the northern US down to central Mexico, where they gather on a few mountaintops for the winter.

In 2012, about 60 million monarchs arrived in the Mexican mountains. That was a record low until the 2013 figures came in – the number arriving was almost half that of the previous year. It was the lowest figure since records began in 1993.

A big problem is the widespread disappearance of the milkweed plant. Monarch larvae eat only milkweed and urbanisation and industrial farming practices have made it scarce.

Hence the research, which was published last April. The researchers found that restricting the monarch larva’s milkweed intake reduces the size of its wings when it emerges from the chrysalis. It is likely that this stunted growth makes the migration much harder work.

Monarchs also seem to need food to maintain their looks. The colours of the orange-and-black wing patterns are deeper, with more striking contrast, in monarchs covering the most distance. It may be that feeding up the larvae to produce better fliers will also produce more beautiful butterflies.

The aesthetic argument is one of very few available to conservationists. Researchers can’t point to any specific benefit that monarchs bring: they don’t seem to play a crucial role in any ecosystem and their removal from specific ecosystems “would probably not have lasting repercussions”, as one report put it. The monarchs don’t contribute anything apart from a beautiful spectacle when they migrate.

British butterflies are even worse off – they don’t have a spectacular migration. In March, the UK government issued a draft of its “pollinator strategy” document, which outlines what might be done about the severe decline in numbers of pollinating insects such as bees, butterflies and moths. The charity Butterfly Conservation said that it “strongly welcomes” the proposed strategy (though it dismisses as “ludicrous” the idea that pesticide companies should self-regulate).

Yet there is a slightly dejected tone to the charity’s chief executive’s observations. He points out that while bees are acknowledged to have economic value as pollinators of agricultural crops, butterflies are not and are therefore less likely to receive government help. In the age of market forces, it is not enough to be beautiful.

However, as the Intergovernmental Panel on Climate Change noted in March, butterflies’ relatively short life cycle and “high dispersal capacity” make them very useful markers of climate change.

That is certainly true of the British butterfly population, which, apart from a few cold-loving species, is thriving in our warming climate. In the past 20 years, for instance, the orange-and-black comma butterfly has spread 137 miles northwards.

If you lived in Edinburgh in the early 1990s, you would not have seen one. Now they’re not an uncommon sight: an effect of global warming that’s hard to complain about.

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 14 April 2014 issue of the New Statesman, Easter Double

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Marching against climate change in the age of Donald Trump

The People’s Climate Movement is as much about politics as science. That's its strength.

Saying goodbye is never easy. But the present generation are facing an awful lot of farewells: to the melting arctic, the dying Barrier Reef, and the general resilience of ecosystems around the world. As Margaret Atwood described it in her essay of the same name: “It’s not climate change, it’s everything change”.

The problem with “everything-change” is that it can be overwhelming. How do you even decide where to start?

The People’s Climate Movement want to begin by making visible the extent of concern out there. This weekend, a coalition of organisations have planned a protest march on the American capital. Between 50,000 -100,000 people are expected to attend, including eco-celebrities Leonardo Di Caprio, Al Gore and Richard Branson.

In London, a group called Campaign Against Climate Change, are co-ordinating a UK-based solidarity event. Protestors will meet at 11.30am in Old Palace yard opposite Parliament, then move to Westminster Bridge, where they will spell out a message to Theresa May: “Trump and May: Climate Disaster”.

For UK campaigners, this is a vital opportunity to raise awareness of the many ways in which action on climate change is under threat. Claire James from CACC outlines the sense of frustration and injustice that many feel with regard to recent government policy: “There have been 12,000 jobs lost last year in the solar industry alone and installation numbers have plummeted. Meanwhile fracking, hugely unpopular, is given determined backing.”

Ahead of the June election, campaigners are using the event to call for specific, cross-party commitments. One, fast-tracking the UK’s delayed Climate Change Plan. Two, ruling out new trade deals that compromise environmental, worker or consumer rights. And three, implementing a fair deal for UK solar and wind industry. “Our action on Saturday is about saying to the government – and to anyone who wants to form the next government – do your policies measure up?” says James.

These concrete political aims are an important way in which the movement differs from last weekend’s March For Science. That protest, inspired by the popularity of the Women’s March earlier this year, kept its message intentionally wide. As one of the London event’s organisers told DeSmog, it placed its emphasis on a generalised “celebration of science”. But this lack of specificity drew criticism from some quarters – for presenting a confusing message about politics' relationship to science.

Generalisation can also risk putting people off joining marches at all. Over the last few months, numerous friends have said they feel uncomfortable joining protests where they’re not sure that the person marching next to them is doing so for the same reasons. They’d feel much happier signing a petition, with a more specific and limited aim, they tell me.

This weekend’s climate marches risk drawing some of the same concerns. “Climate-change has become a synecdoche, a surrogate, for many causes in today’s world – social justice, the protection of nature, the rights of future generations, the defence of science,” says Professor Mike Hulme from King's College London. “Marches such as this give political voice to anti-establishment protest, but they don’t stop the climate changing.”

In addition, not all who want to see climate change prioritised by governments may agree over the exact course of action – with outright opposition to fracking, for instance, or to a third runway at Heathrow.

But this weekend’s movement also appears to have taken these lessons on board. First, they are putting their political aims up front. According the US event’s website, whereas the March for Science strove to be non-political, this movement “believes strongly in the need to call out the politicians.”

The link to the Paris Climate Treaty is helpful in this respect. The People’s Climate Movement traces its birth back to September 21 2014, the eve of the UN climate summit, when 400,000 people marched through New York demanding action on the climate crisis. This gives the movement a clear piece of legislation to both celebrate and defend.

And the London-based event is also attempting to re-think and expand what street-protests can achieve. “We’re doing a smaller action rather than a big march,” explains Claire James, “but we’re trying to have a real focus with the speakers on ‘what next’”. After the protest in Westminster, attendees are invited to join an afternoon of free food, activities and music, hosted by the food waste campaign Feedback. Here there will be even further opportunity to learn about the many ways – from divestment campaigns to local renewable energy groups – in which people can help press for change.

In this respect, public action against the climate crisis promises not to end when the walking does. And while protests won't stop climate change in themselves, joining a march can be a powerful reminder that we are not in this crisis alone.

India Bourke is an environment writer and editorial assistant at the New Statesman.

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