“After travelling for some hundreds of yards, often for more than half a mile, the formicarium is reached. It consists of low wide mounds of brown clayey-looking earth, above and immediately around which the bushes have been killed by their buds and leaves having been persistently bitten off as they attempted to grow after their first defoliation. Under high trees in the thick forest the ants do not make their nests, because, I believe, the ventilation of their underground galleries, about which they are very particular, would be interfered with, and perhaps to avoid the drip from the trees. It is on the outskirts of the forest, or around clearings or near wide roads that let in the sun, that these formicariums are generally found. Numerous round tunnels, varying from half an inch to seven or eight inches in diameter, lead down through the mounds of earth; and many more from some distance around also lead underneath them. At some of the holes on the mounds ants will be seen busily at work bringing up little pellets of earth from below and casting them down on the ever-increasing mounds, so that its surface is nearly fresh and new-looking.... “The ceaseless toiling hosts impress one with their power, and one asks, What forests can stand before such invaders? How is it that vegetation is not eaten off the face of the earth? Surely nowhere but in the tropics, where the recuperative powers of Nature are immense and ever active, could such devastation be withstood.... None of the indigenous trees appear so suitable for them as the introduced ones....