"Don't feed 'em on pears, does it?" asked Willie.
"Not exactly; they do not get their living directly from the tree; but they feed on it indirectly. The fact is, this species keeps a kind of ant cows. These are minute insects, which attach themselves to the interior of the tree, and live on its juices. They give out a honey-like liquid, of which the ants are very fond, and lap up with great eagerness. You see thus that there are various ways in which plants feed the ants which protect them from other insects."
"Are there any other ants that live on trees?" asked Harry.
"Yes, indeed. Ants are very apt to take possession of hollow trees. They build thin partitions, which divide the interior of the tree into halls, galleries, and saloons, and they live there thoroughly sheltered from the weather. The Ethiopian ants hollow out long galleries, and use the finely powdered wood which has fallen to the bottom of the tree to stop up every chink in the floors, to make partitions, and to fill up useless apartments. There are also yellow ants which construct entire stories of this decayed wood. They mix it with a little earth and spider's web, and thus make it into a sort of papier-maché."
"Don't think that's so awful smart," protested Willie. "Jess don't the wasps an' the hornets make paper nests too?"
"Very true," replied his uncle. "There is another curious ant, though, which makes its nest out of leaves. These are large, strong leaves, but the little creatures somehow draw their edges together, and gum them fast, so that they make themselves a close, roomy shelter inside. They have been seen at work, thousands of them tugging away for dear life at the edges of the leaves. If they are startled, and made to loose their hold of the edge, it flies back so strongly that it is a marvel how they ever drew it in."
"Don't they sometimes build very large nests on the ground," asked Harry—"much larger than the little ant-hills we see about here?"
"I should think so, indeed! Why, the common red ant of England builds a nest of any rubbish it can find, such as straw, leaves, and bits of wood mixed with earth, often as large as a small hay-cock. But this is a trifle, compared with some tropical ant-hills. Travellers in Guiana describe ant-hills which are fifteen or twenty feet high, and thirty or forty feet wide at the base. You might well fancy they were houses for elephants, instead of for ants."
"I should imagine they must be elephantine ants," remarked Harry.
"Not at all. There is a very small ant in New South Wales whose hills are eight or ten feet high. But this is not all; these great mounds are only the upper part of the ant city. It extends as deeply under-ground. There is one ant described that builds a nest of forty stories, twenty above and twenty under ground. These stories are divided into numerous saloons and apartments, with narrow galleries, and inclined planes for stairways. The partitions are usually very thin, but the ceilings are often supported by pillars and buttresses, just like our great halls."