The butterfly, the ant, and other natural mimics


It sounds like one of Aesop's fables but the story of the blue butterfly and the red ant is probably not one you would like to send your children off to sleep with. The caterpillar of the blue butterfly is "adopted" by the red ant which takes the butterfly larva back to its nest where it treats it like one of its own brood feeding it until it is old enough to turn into an adult butterfly.

The caterpillar, however, repays the ant's generous hospitality by greedily eating as much food as it can and gobbling up the ant's offspring as a tasty side dish.

All five species of large blue butterflies in Europe engage in this form of parasitism on red ants and now scientists have worked out the trick that allows them to do it the caterpillars cover themselves in a chemical that makes them smell like orphaned baby ants.

Researchers have found that the organic molecules secreted on the skin of the blue caterpillars closely match those on the skin of the red ant larvae. What is more, the closer the chemical cocktail is, the stronger the attraction of the ant to the caterpillar.

The findings should help conservationists in their attempts at reintroducing large blue butterflies which are endangered by making sure the chemistry of the caterpillars and the ants match each other as closely as possible.

David Nash of the University of Copenhagen, who led the study published in the journal Science, said the results were a vivid demonstration of the evolutionary "arms race" that can escalate between parasites and their hosts.

"Parasites are always trying to better adapt to their hosts to parasitise them whereas their hosts are experiencing selection pressures to avoid being parasitised," Dr Nash said.

"It means there can be an ongoing evolutionary arms race between the parasite and its host. There have been some previous studies on microscopic organisms showing this can occur in the laboratory but what we have here I think is one of the first cases where we have clear evidence that this has been happening out in the field."

The scientists studied dozens of red ant colonies on an island off the Danish coast and, in each nest they examined, they counted the number of caterpillars of the Alcon large blue butterfly that they found living there

Alcon blue butterflies lay their eggs on the marsh gentian plant and its caterpillars grow in the usual way by feeding on the plant's leaves. But, at the fourth stage of growth, the caterpillars gently lower themselves to the ground on silken threads.

"The caterpillars first start developing on a food plant but once they reach a certain stage they leave the food plant and wait on the ground to be discovered by one of these ants," Dr Nash said.

Often in nature, ants would make a meal of a caterpillar but in the case of the large blues, the passing ants pick them up gently and take them lovingly back to their nest the question was why?

"The butterfly gets into the ant nest by mimicking the surface hydrocarbons, the surface chemicals that the ants have on their own brood," Dr Nash said.

"They are producing this signal that says 'I'm an ant brood'. We've been able to show that the closer that mimicry is, the faster they are picked by the ants and taken back into the ant nest and put amongst the brood.

"Once they are there among the brood they become highly virulent parasites. They eat some of the brood and they also get fed by some of the worker ants, and they get fed in preference to the ants' own brood," he said.

Two species of Myrmica red ants were found to be routinely parasitised by the Alcon blue butterfly but the scientists also discovered that one of these species is far more heavily exploited by the blue's caterpillars than the other species of ant.

"We know that almost any ant within this Myrmica group of ants will pick up a caterpillar and take it back to the nest, but it is only within these two species that it will survive," Dr Nash said.

"We have one species where the ant is exploited at a relatively constant rate and we have another species where, when it is common, it is exploited even more than you'd expect but, when it is rare, it is hardly exploited at all," he said.

The difference in the exploitation rates between the two species of red ant helps the blue butterflies survive because if it relied on just one species there would be a danger of it overexploiting its only host. The second host species means there is a back-up in times of ant scarcity, Dr Nash said.

Parasite peril

Blue butterfly

The large blue butterfly has a complex, parasitic relationship with red ants which involves its caterpillars being taken into the ant's nest and fed. The caterpillars manage this by mimicking the smell of the ants' own larvae


One of the most famous con tricks in nature is the story of the cuckoo. It lays an egg in the nest ofanother species of bird for it to unwittingly raise the chick as is own. The cuckoo's eggs often mimic the colours and patterns of the eggs of the host species to minimise the risk of rejection


The flowers of some species of orchid, such as the Australian hammer orchid, resemble female bees or wasps. This attracts male insects, which become dusted with pollen


This harmless flying insect lookssuperficially like a wasp. The yellow and black stripes are designed to mimic the warning coloration of stinging insects to help it avoid being attacked and eaten by birds, which have learnt from experience to avoid the striped colours of stinging insects

Have you tried new the Independent Digital Edition apps?
Arts and Entertainment
Kanye West, performing in New York last week, has been the subject of controversy as rock's traditional headline slot at Glastonbury is lost once again
Arts and Entertainment
The Ridiculous Six has been produced by Adam Sandler, who also stars in it
filmNew controversy after nine Native American actors walked off set
Life and Style
Google celebrates Bartolomeo Cristofori's 360th birthday
techGoogle Doodle to the rescue
Life and Style
Drinking - often heavily - is a running theme throughout HBO's Game of Thrones adaptation
food + drink
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Senior Digital Marketing Consultant

£28000 - £45000 per annum: Recruitment Genius: A Senior Digital Marketing Cons...

Recruitment Genius: Assistant Stores Keeper

£16640 - £18500 per annum: Recruitment Genius: An Assistant Stores Keeper is r...

Recruitment Genius: Claims Administrator

£16000 - £18500 per annum: Recruitment Genius: This is an excellent opportunit...

Recruitment Genius: Software Developer - C# / ASP.NET / SQL

£17000 - £30000 per annum: Recruitment Genius: Developer required to join a bu...

Day In a Page

Fishing for votes with Nigel Farage: The Ukip leader shows how he can work an audience as he casts his line to the disaffected of Grimsby

Fishing is on Nigel Farage's mind

Ukip leader casts a line to the disaffected
Who is bombing whom in the Middle East? It's amazing they don't all hit each other

Who is bombing whom in the Middle East?

Robert Fisk untangles the countries and factions
China's influence on fashion: At the top of the game both creatively and commercially

China's influence on fashion

At the top of the game both creatively and commercially
Lord O’Donnell: Former cabinet secretary on the election and life away from the levers of power

The man known as GOD has a reputation for getting the job done

Lord O'Donnell's three principles of rule
Rainbow shades: It's all bright on the night

Rainbow shades

It's all bright on the night
'It was first time I had ever tasted chocolate. I kept a piece, and when Amsterdam was liberated, I gave it to the first Allied soldier I saw'

Bread from heaven

Dutch survivors thank RAF for World War II drop that saved millions
Britain will be 'run for the wealthy and powerful' if Tories retain power - Labour

How 'the Axe' helped Labour

UK will be 'run for the wealthy and powerful' if Tories retain power
Rare and exclusive video shows the horrific price paid by activists for challenging the rule of jihadist extremists in Syria

The price to be paid for challenging the rule of extremists

A revolution now 'consuming its own children'
Welcome to the world of Megagames

Welcome to the world of Megagames

300 players take part in Watch the Skies! board game in London
'Nymphomaniac' actress reveals what it was really like to star in one of the most explicit films ever

Charlotte Gainsbourg on 'Nymphomaniac'

Starring in one of the most explicit films ever
Robert Fisk in Abu Dhabi: The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers

Robert Fisk in Abu Dhabi

The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers
Vince Cable interview: Charging fees for employment tribunals was 'a very bad move'

Vince Cable exclusive interview

Charging fees for employment tribunals was 'a very bad move'
Iwan Rheon interview: Game of Thrones star returns to his Welsh roots to record debut album

Iwan Rheon is returning to his Welsh roots

Rheon is best known for his role as the Bastard of Bolton. It's gruelling playing a sadistic torturer, he tells Craig McLean, but it hasn't stopped him recording an album of Welsh psychedelia
Russell Brand's interview with Ed Miliband has got everyone talking about The Trews

Everyone is talking about The Trews

Russell Brand's 'true news' videos attract millions of viewers. But today's 'Milibrand' interview introduced his resolutely amateurish style to a whole new crowd
Morne Hardenberg interview: Cameraman for BBC's upcoming show Shark on filming the ocean's most dangerous predator

It's time for my close-up

Meet the man who films great whites for a living