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Wherever you go
in tropical America, you're likely to see leafcutter ants.
They build huge nests,
sometimes 30 feet across and 20 feet deep, which have several entrances,
perhaps hundreds of yards apart. There can be two or three
million ants in a single colony.
Inexplicably, I don't
have a good photograph of one of these nests, although I've seen a few
of them. However, here's a photo of a construction effort by
these ants which is even more frequently seen - one of the small highways
which they use to do their work. They're meticulous in keeping
it free of debris, plants and other obstructions. |
| The ants get their
name from the way they cut leaves from trees, which they then haul back
to their nest. They don't eat the leaves, instead they use
it as compost to grow a particular type of fungus, which doesn’t grow anywhere
other than in leafcutter ant nests. The ants then eat the fungus,
and feed it to their young. The fungus is grown in football
sized chambers inside the nest. There can be 300 or more of
these chambers inside the nest, and all of the earthworks to build them
might involve the removal of 18,000kg of earth during the lifetime of the
nest. |
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| The ants consume
up to a fifth of all forest vegetation in the areas they’re found, but
the ants rotate the trees they harvest so that they aren’t killed.
Leaves from any one tree are only taken to part of the nest, rather than
distributed throughout the nest. This prevents a widespread
disaster if the leaves turn out to be infected, or toxic to the fungus. |
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| The ant standing
on top of this leaf is much smaller than the leafcutter ant worker below
it - but it's actually just a different caste of leafcutter.
The small ants ride around on the leaves looking for harmful foreign matter
and intruders like eggs which certain species of fly lay on the leaves
in the hope that they’ll be carried into the nest. |
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All of this material
pouring in has to end up somewhere, otherwise the nest would soon be full.
Here you can see workers carrying used compost from the nest and tossing
it onto a two-foot high garbage pile. |
| The ants which cut
and carry the leaves are much larger than the sentinels, but there's another
caste of leafcutter ant which is even bigger - the soldiers.
To see a soldier,
all you have to do is stomp on the ground outside a nest, and soon they'll
start pouring out the entrances, like this one here. |
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| They're formidable
critters, with large spikes on their bodies and aggressive personalities. |
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| Their jaws are easily
large enough and strong enough to cut up human skin - so with the
soldiers starting to crawl over us, our guide suggested that we beat a
retreat! |
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