A Near-Extinct Blue Butterfly Flourishes Again, Thanks to a Red Ant

By Eliza Strickland | June 16, 2009 8:45 am

blue butterflyIn a rare conservation success, a beautiful butterfly species that was headed for extinction has been brought back from the brink, thanks to careful biological observations of the insect‘s life cycle. The mysterious disappearance of the Large Blue Butterfly across most of northern Europe was originally put down to its popularity among insect collectors [Telegraph]. Then biologist Jeremy Thomas spent six summers in the 1970s studying the very last colony of large blue butterflies in the United Kingdom, and determined that the butterflies were dependent on one species of red ant for their survival–and those ants were losing their habitat.

The butterflies lay their eggs on flowering thyme plants, and the hatched caterpillars fall to the ground and begin to impersonate immature red ants. They secrete chemicals and even make noises that make the red ants believe they are wayward grubs. The ants then mistakenly carry the caterpillars to their underground homes and keep looking after them even though the adopted intruders gobble ant grubs for 10 months before forming a chrysalis and flying away as adult butterflies [Reuters].

However, the red ants live in fields where the grass is short enough to let the sun warm the soil. Historically, rabbits had kept the grass short, but in the mid-1950s rabbit populations were suddenly devastated by the plague-like disease myxomatosis [The Independent]. Farmers had also been gradually halting the practice of grazing their cattle, which allowed pastures to get overgrown. When the grass grew less than one inch taller than usual, the increased shade cooled the soil by more than three degrees Fahrenheit, Thomas found, and the red ants vanished. “To human beings the change looks like absolutely nothing. But when you are on the scale of insects it makes a huge difference to the micro-habitats where they live,” he said [Reuters].

Thomas worked out the ecological pressures on the large blues in the 1970s, but he was to late to save the species in Britain; the last colony there died out in 1979. But the knowledge to bring it back and keep it was now in place; and in 1983 … he brought large blue caterpillars from Sweden and released them [The Independent]. Cows were brought in to graze in the reintroduction sites, and both the red ants and the blue butterflies found their niches in the ecosystem again. In a paper that will be published online this week by Science, researchers report that there are now more than 30 colonies of large blue butterflies in the United Kingdom, with an estimated population of about 20,000…. Broadcaster Sir David Attenborough commented: “The restoration of the large blue butterfly to Britain is a remarkable success story, illustrating the power of ecological research to reverse damaging environmental changes” [BBC News].

Related Content:
80beats: Tricky Caterpillars Impersonate Queen Ants to Get Worker Ant Protection

Image: David Simcox, Center for Ecology and Hydrology

CATEGORIZED UNDER: Environment, Living World
  • johnn costello

    bring some to New Jersey, PLEASE

  • http://ashabot.blogspot.com asha

    What a wonderful success. Bravo! And so much better use of intelligence than building weapons of mass destruction.

  • Jeremiah

    A slendid treat for my eyes to see. I will definitely share this achievement with others.

  • Alex B

    WOW! Amazing! What a testament to the well balanced and delicate web of ecosystems! Its so humbling/scary to see how such a miniscule change can wipe out a whole species! Myxomatosis killed the rabbits, this allowed the grass to get too long, that cooled the ground, the ants left because of the temp. change, and the caterpillar’s lifecycle was disturbed! And they say that there’s no way that humans are affecting earth’s climate? Ya rite!

  • brenatevi

    “And they say that there’s no way that humans are affecting earth’s climate? Ya rite!” I take exception to this as someone that thinks AGW is overstated; I can’t speak for anyone else, but I’ve never said that humans don’t affect climate.

    You can think whatever you want about my opinion, but think on this: how many species have become extinct without human interference? And yet another way of looking at it: why is extinction seen as so bad? I know that the word “biodiversity” gets thrown around a lot, yet the Earth has seen extinctions that have wiped out 70%+ of species, multiple times, and yet, here we are. So… At what point does it sink in that the world changes with or without humanity’s input?

    On the other hand, I find it gratifying that people were clever enough to save this species, even if for a little while.

  • Skadoosh

    How come no one cares about the red ants? Capitalism picks winners and losers too, but libs aren’t so fond of that “natural habitat.” Haha, hypocrites…

  • katwagner

    Omgsh, this has to be the coolest thing I’ve read all week. Let’s hear it for science, observation and getting the story straight. We can save the whole planet if we try hard enough!

  • dolphinfriend

    Wow! That’s pretty cool. I wonder why the ants take in the caterpillar when it will just eat their babies. They have to gain something. Poor red ants. I hope that people will help the red ants and the butterflies.

  • Brian

    Were these the ordinary red ants I’ve grown up around, or some sorta exclusive, rare red ants?

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