Homes Without Hands: Being a Description of the Habitations of Animals, Classed According to Their Principle of Construction

The Saüba Ant is restricted to tropical America, where it exists in such vast profusion, that it oftentimes takes forcible possession of the land, and drives out the human inhabitants who have cultivated and planted it. Broad columns of these ants may be seen marching along, each individual carrying in its jaws a circular piece of leaf, about the size of a sixpence, which is held vertically by one of its edges. In the British Museum there is a specimen of a Saüba Ant, with the leaf still grasped in its jaws, the ruling passion strong in death. From this curious habit the creature is sometimes called the Parasol Ant, and many persons have thought that the leaves are carried in order to protect the insect against the hot sunbeams. The real reason, however, has been discovered by Mr. H. W. Bates, who has studied with great care the habits of this remarkable insect, and has disentangled its history from many doubts and difficulties.

There are, as is usual with all ants, three distinct ranks—namely, the winged, the large-headed, or soldiers, as they are popularly called, and the ordinary workers. The large-headed individuals are subdivided into two classes, namely, the smooth-heads and rough-heads, the former wearing a polished, horny, translucent helmet, and the head of the latter being opaque and covered with hair. The large-headed ants do no ostensible work, all the labor falling to the lot of the workers. These creatures make raids upon the trees, always giving the preference to cultivated trees, such as the orange and the coffee, and cut away the leaves so fast that the growth is stopped, and the entire plant sometimes dies. The use of the leaves is to thatch the domes of their curious edifices, and to prevent the loose earth from falling in. Some of these domes are of gigantic dimensions, measuring two feet in height and forty feet in diameter, the mightiest efforts of man appearing small and insignificant when the comparative dimensions of the builders are taken into consideration. Division of labor is carried out to a wonderful extent in these buildings, for the laborers which gather and fetch the leaves do not place them, but merely fling them down on the ground, and leave them to a relay of workers, who lay them in their proper order. As soon as they have been properly arranged, they are covered with little globules of earth, and in a very short time they are quite hidden by their earthy covering.

The functions performed by the large-headed ants are not very evident. Those with smooth fronts seem to do nothing but walk about. They do not fight like the soldier-termites, nor do they appear to exercise any rule over the workers. Moreover, they have no sting, and even when assaulted they scarcely ever resent the insult. The hairy-headed variety is still more enigmatical in its duties. “If the top of a small, fresh hillock, one in which the thatching process is going on, be taken off, a broad cylindrical shaft is disclosed, at a depth of about two feet from the surface. If this be probed with a stick, which may be done to the extent of three or four feet without touching the bottom, a small number of colossal fellows will slowly begin to make their way up the smooth sides of the mine. Their heads are of the same size as the class No. 2, but the front is clothed with hairs instead of being polished, and they have in the middle of the forehead a twin ocellus, or simple eye, of quite different structure from the ordinary compound eyes on the sides of the head. This frontal eye is totally wanting in the other workers, and is not known in any other kind of ant. The apparition of these strange creatures from the enormous depths of the mine reminded me, when I first observed them, of the Cyclops of Homeric fable. They were not very pugnacious, as I feared they would be, and I had no difficulty in securing a few with my fingers. I never saw them under any other circumstances than those here related, and what their special functions may be I can not divine.”

The subterranean galleries which these creatures form are of almost incredible extent—so vast, indeed, and so complicated, that they have never been fully investigated. A conjecture as to their size may be formed from the fact, that when sulphur smoke was blown into a nest, one of the outlets was detected at a distance of seventy yards. The Saüba has often done considerable damage to property, having pierced the embankment of a large reservoir, and let out all the water before the damage could be detected.

The winged class is composed of the perfect male and female, which take their departure from the nest in January and February. They are quite unlike the other workers and soldiers, being larger and darker, with rounder bodies and a more bee-like aspect. The female is a really large insect, measuring more than two inches in expanse of wing, and the body being equal in size to a hornet; but the male is much smaller, as is generally the custom with the insect race. Of the hosts which pour out of the nests, only a few individuals remain after a space of twelve hours, the rest having been devoured by birds and other insect-eating creatures. Those which survive address themselves to the founding of new colonies; and so prolific are these insects, that, in spite of the vast destruction wrought among the winged individuals, to whom alone the task of reproduction belongs, man often has to retire before them, and even his art can not conquer them.

The Saüba is one of the very few ants that does not attack other creatures. The real Driver, or VISITING, or FORAGING Ant, of which there are several species, belongs to another genus, Eciton, which will be described among the building-insects.

Most of the British ants are among the burrowers, hollowing out subterranean abodes of great extent, and constructing them upon some intricate plan, the principle of which is not very evident. The Dusky Ant (Formica fusca) generally prefers banks with a southern aspect, in which it forms its elaborate dwelling. Like many other ants, it is somewhat of a builder as well as a miner, and can raise story upon story, as well as add them by excavation. This task is achieved by covering the former roof with a layer of fresh and moist clay, and converting it into a floor for the next story. Dry weather has the effect of retarding the ants in their labors, because they find a difficulty in procuring sufficient moisture wherewith to mix the clay.

The muscular power and the energy and endurance of the ant are truly wonderful; and if a human being, even if aided by tools, could perform such a day’s work as was achieved by a single ant without them, he would be a wonder of the world. M. Huber had the curiosity and good sense to devote the whole of a rainy day to watching the proceedings of a single Dusky Ant. The insect began by scooping out a groove in the earth, about a quarter of an inch in depth, kneading the earth, which it removed into little pellets, and placing them on each side of the groove, so as to form a kind of wall. The interior of the groove was beautifully smooth and regular, and when completed it looked very like a railway cutting, and performed a similar office. After completing this task, it looked about and found that there was another opening in the nest to which a road must be made, and straightway set to work upon a second sunken path of a similar character, parallel to the first, and being separated from it merely by a wall of a third of an inch in height.

Compare the size of an ant with that of a man, and then see how vast are the powers of so small a creature. Taking all the calculations in round numbers, and very much to the disadvantage of the ant, we find that a single man, who would have achieved a similar work in a single day, must have acted as follows:

He must have excavated two parallel trenches, each of seventy-two feet in length and four feet six inches in depth; he must have made bricks from the clay he dug out, and with them built a wall along each side of the trenches, from two to three feet in height and fourteen or fifteen inches in thickness; and lastly, he must have gone over the whole of his work again, and smoothed the interior until it was exactly true, straight, and level. All this work must also have been done without the least assistance, and the ground must be supposed to be filled with huge boulders, and covered with tree-trunks, broken logs, and other impediments.

The most admirable subterranean architecture is perhaps that of the Brown Ant (Formica brunnea), a species which is not very commonly known in this country, and is probably confined to certain localities. Its habitation and the mode of its construction have been carefully noted by M. Huber.

This ant works mostly at night, and during light, misty rain, the sunbeams being obnoxious, and heavy showers causing much inconvenience. The nest is a most complicated structure, composed of a series of stories, often reaching thirty or forty in number, and generally being built in a sloping direction. These stories are not composed of regular cells, like those of the bee, wasp, and hornet, but of chambers and galleries of very irregular form and dimensions, beautifully smoothed in the interior, and about one fifth of an inch in height. The walls are about the twenty-fourth of an inch in thickness. The object of so many stories is to be able to regulate the heat and moisture of their establishments. If, for example, the sun is not very powerful, and the instinct of the little insects tells them that more heat is required in order to hatch the pupæ which are undergoing their metamorphosis, they take up the white burdens and carry them into the upper chambers, where the heat is greater than below.

Again, if there should be a heavy rain, which floods all the lower stories, nothing is easier for the inhabitants than to remove themselves and brood into the upper sets of chambers, where they will be secure from the inundation. On those days when the sun is peculiarly hot, the ants secure a more equable temperature, by removing the young brood to the central flats, if they can be so called, while they themselves can obtain the needful moisture from the lower parts of the nest, to which the sunbeams can not penetrate. Were it not for this provision which they instinctively make, all building operations would be stopped during a drought, whereas, by descending to the cellars or crypts of the mansion, the ants can obtain sufficient clay for ordinary work.

In order to watch the ants closer, Huber constructed a kind of vivarium in which they could work, and supplied them with earth, sand, and other necessaries. As, in this artificial state of existence, the insects could not procure moisture from the depths of the earth, moisture from other sources was necessary. Whenever the insects had ceased to work, they could almost always be induced to renew their labors by dipping a stiff brush in water, and striking the hand upon it in such a manner that the water descended like very fine rain upon the earth. As soon as the formerly quiescent ants felt the grateful shower, they regained their activity, ran about with renewed energy, and set to work upon the soil, moulding it into little pellets, and testing each tiny ball with their antennæ before they applied it to the purposes for which it was made.