Leaf Cutter Ants at Barro Colorado

In places, the forest floor appeared to be alive, a moving carpet of green. This hallucination was brought about by the streams of leaf-cutting ants hurrying back to their nests with their booty, a triangular piece of thumbnail-sized green leaf, slung over their shoulders. From the tree of their choice ( which they were busily dissecting ) to the nest may be several hundred yards, and so these columns of green wend their way over the dark forest floor, over logs and under bushes in a steady stream that on close inspection looks like a Lilliputian regatta, all the boats having green sails.
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We moved on into the forest, stepping carefully over the columns of leaf-cutters. So numerous were they that you wondered why the whole forest was not defoliated. This leaf-gathering is really a form of gardening, for the ants carry the leaves to their vast underground homes ( sometimes a quarter of an acre in extent ) and here they rot the leaves down into a mulch on which they grow the fungi which is their food.