On a wing and without a prayer – the decline of the monarch butterfly

Out of America: More GM crops mean more herbicides – which destroy the food the insects need for their epic migration

Share
Related Topics

As you read this, the first intrepid invaders are fluttering northward across the Rio Grande that separates Mexico from the United States. Within days, they will be followed by millions of others, in one of earth's most extraordinary rites of spring. The great migration of the monarch butterfly is under way – and never has one been watched so closely, and so anxiously.

Forget the politicians and the rest of the human activity that makes Washington tick. The real wonders of this place, I have come to realise, are natural – and two of them in particular. The first are the Brood X cicadas, the larvae of which grow underground for 17 years before emerging in late spring to spend six short weeks in our sunlit world, in which time they mate, breed and die. They are sluggish creatures and seemingly half blind, to judge by the way they splatter into walls and windows. They also make a deafening din that makes summer's standard cicada buzz a whisper. Cicada-fanciers say they are delicious deep fried, but to my shame I've never dared to try one. More to the point, they appear a mere five times in the average human lifetime. Currently the larvae, which last surfaced midway through the George W Bush presidency, have served slightly over half their subterranean sentence and will reappear in 2021 (when, who knows, Hillary Clinton may be embarking on her second White House term).

But the glorious visitation of the monarchs takes place every year. Here in DC, we're on the edge of the migration, but in May a few northbound ones, instantly recognisable through their gaudy gold and black colouring, usually drop into the garden to refuel. More may be seen in late September or October on their way back to Mexico, still a month or two's travel away. This year, however, there may be fewer than ever. The monarch, alas, is in big trouble.

In its way, a monarch's life cycle is even more extraordinary than that of Brood X cicadas. It winters in one of just a dozen patches of fir forest in the Sierra Madre mountains, to the west of Mexico City. In early to mid-March it begins the epic northward journey. When the monarchs reach the southern US they lay their eggs, and a new generation is born, with an overall life cycle of up to eight weeks.

Twice more this process – egg to caterpillar to chrysalis to butterfly – repeats itself as the monarchs fly north to the Canadian border and beyond, where a fourth generation of monarchs is born. But this final generation of the year is different. It lives for eight or nine months, not weeks, and does not breed until the very end. Its mission is to fly back to those same fir trees whence its great-great-grandparents departed eight or nine months earlier. There they wait out the winter before the whole cycle starts again.

How the monarchs navigate their 4,000-mile round trip no one is quite sure. Creatures of many species migrate, but usually with a parent to show them the way. No such luck for the monarch; the last members of the species to ply the route were four generations ago. Yet somehow they manage; year after year, monarchs west of the Rockies go back to a few similar acres of highland forests in southern California, while east of the Rockies the butterflies return to Mexico.

These latter could take a wrong turn to Florida; they could get lost over the Gulf of Mexico and drown. But most don't. Instead, they home in on a 50-mile-wide corridor across the Rio Grande, some 200 miles due west of San Antonio, that leads to safety. Instinctively, therefore, they can measure both latitude and longitude – something, incidentally, that humans couldn't manage until the 18th century, when John Harrison invented his famous clock for seafarers.

Last week, however, brought alarming news. According to the new census by the Mexican authorities, the number of returning monarchs last winter was the lowest in two decades. Obviously, the number of butterflies cannot be counted, but the area of forest occupied by their colonies dropped by 60 per cent from the year before, to just 2.94 acres. And while year-on-year fluctuations are normal, a long-term downward trend is unmistakable.

The reasons are several. A prime one used to be logging that destroyed the butterflies' winter habitat. But the Mexican authorities have created a 200 square mile biosphere reserve where tree harvesting is banned. More important, local people have realised that the butterflies are a tourist attraction far more valuable than hardwood.

Another factor, inevitably, has been climate change. On their journey north, the butterflies were assailed by the hottest year on record in the US. The early onset of heat upset the monarchs' breeding rhythm, while the scorching summer dried out eggs, and reduced the nectar content of flowers. On the way back, they encountered Texas's worst drought in decades.

Most serious of all have been farming developments in North America, where genetically modified corn and soybean allow the use of herbicides that wipe out the milkweed whose nectar feeds the caterpillars. Milkweed is not only an essential food; it provides a poisonous toxin that monarchs store in their bodies, making them unpalatable to birds and other predators. Indeed, the gaudy stripes of both caterpillar and mature butterfly are nature's way of saying "don't touch".

All may not be lost. Sooner or later the rains will return, and midwestern summers may turn milder for a while. Local US authorities may replenish the milkweed to help to preserve a creature that is a minor national institution, a piece of Americana in its own right. And every fan of the monarch, from DC to the Rockies, is demanding it succeeds.

React Now

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

Austen Lloyd: Private Client Solicitor - Oxford

Excellent Salary : Austen Lloyd: OXFORD - REGIONAL FIRM - An excellent opportu...

Austen Lloyd: Clinical Negligence Associate / Partner - Bristol

Super Package: Austen Lloyd: BRISTOL - SENIOR CLINICAL NEGLIGENCE - An outstan...

Recruitment Genius: Sales Consultant - Solar Energy - OTE £50,000

£15000 - £50000 per annum: Recruitment Genius: Fantastic opportunities are ava...

Recruitment Genius: Compute Engineer

Negotiable: Recruitment Genius: A Compute Engineer is required to join a globa...

Day In a Page

Read Next
Syrian refugee 'Nora' with her two month-old daughter. She was one of the first Syrians to come to the UK when the Government agreed to resettle 100 people from the country  

Open letter to David Cameron on Syrian refugees: 'Several hundred people' isn't good enough

Independent Voices
Amjad Bashir said Ukip had become a 'party of ruthless self-interest'  

Could Ukip turncoat Amjad Bashir be the Churchill of his day?

Matthew Norman
Syria crisis: Celebrities call on David Cameron to take more refugees as one young mother tells of torture by Assad regime

Celebrities call on David Cameron to take more Syrian refugees

One young mother tells of torture by Assad regime
The enemy within: People who hear voices in their heads are being encouraged to talk back – with promising results

The enemy within

People who hear voices in their heads are being encouraged to talk back
'In Auschwitz you got used to anything'

'In Auschwitz you got used to anything'

Survivors of the Nazi concentration camp remember its horror, 70 years on
Autumn/winter menswear 2015: The uniforms that make up modern life come to the fore

Autumn/winter menswear 2015

The uniforms that make up modern life come to the fore
'I'm gay, and plan to fight military homophobia'

'I'm gay, and plan to fight military homophobia'

Army general planning to come out
Iraq invasion 2003: The bloody warnings six wise men gave to Tony Blair as he prepared to launch poorly planned campaign

What the six wise men told Tony Blair

Months before the invasion of Iraq in 2003, experts sought to warn the PM about his plans. Here, four of them recall that day
25 years of The Independent on Sunday: The stories, the writers and the changes over the last quarter of a century

25 years of The Independent on Sunday

The stories, the writers and the changes over the last quarter of a century
Homeless Veterans appeal: 'Really caring is a dangerous emotion in this kind of work'

Homeless Veterans appeal

As head of The Soldiers' Charity, Martin Rutledge has to temper compassion with realism. He tells Chris Green how his Army career prepared him
Wu-Tang Clan and The Sexual Objects offer fans a chance to own the only copies of their latest albums

Smash hit go under the hammer

It's nice to pick up a new record once in a while, but the purchasers of two latest releases can go a step further - by buying the only copy
Geeks who rocked the world: Documentary looks back at origins of the computer-games industry

The geeks who rocked the world

A new documentary looks back at origins of the computer-games industry
Belle & Sebastian interview: Stuart Murdoch reveals how the band is taking a new direction

Belle & Sebastian is taking a new direction

Twenty years ago, Belle & Sebastian was a fey indie band from Glasgow. It still is – except today, as prime mover Stuart Murdoch admits, it has a global cult following, from Hollywood to South Korea
America: Land of the free, home of the political dynasty

America: Land of the free, home of the political dynasty

These days in the US things are pretty much stuck where they are, both in politics and society at large, says Rupert Cornwell
A graphic history of US civil rights – in comic book form

A graphic history of US civil rights – in comic book form

A veteran of the Fifties campaigns is inspiring a new generation of activists
Winston Churchill: the enigma of a British hero

Winston Churchill: the enigma of a British hero

A C Benson called him 'a horrid little fellow', George Orwell would have shot him, but what a giant he seems now, says DJ Taylor
Growing mussels: Precious freshwater shellfish are thriving in a unique green project

Growing mussels

Precious freshwater shellfish are thriving in a unique green project