CHAPTER VIIIBEES AND ANTS—A ROBBER MOTH—ANTS THAT KEEP COWS AND SLAVES—ANTS THAT ARE HONEY-POTS—ANTS THAT SOW AND REAP.
BEES AND ANTS—A ROBBER MOTH—ANTS THAT KEEP COWS AND SLAVES—ANTS THAT ARE HONEY-POTS—ANTS THAT SOW AND REAP.
The most wonderful of all insects—that, at least, would be the general opinion—are bees and ants. As bees are so very well known, and kept by so many people, I will not say much about them here, which will leave more space for the ants. Of the two, bees perhaps are the finer architects, for nothing quite so wonderful as their rows of hexagonal cells is to be found in an ant’s-nest. “He must be a dull man,” says Darwin, “who can examine the exquisite structure of a comb, so beautifully adapted to its end, without enthusiastic admiration”; and he goes on to observe that “bees have practically solved a recondite problem, and have made their cells of the proper shape to hold the greatest possible amount of honey, with the least possible consumption of precious wax in their construction.” No doubt these wonderful cells are now made instinctively, yet the bees can adapt their architecture to special circumstances, which shows the possession of reasoning power. Thus, should a piece of the comb fall down, they will not only fix it, by wax, in its new position, but,what is much more extraordinary, will strengthen the attachments of the other combs, lest they should fall too—for there can be no other reason for such an act. Bees, again, are sometimes much annoyed by the death’s-head moth which enters the hive at night, and devours the honey, apparently without danger to itself, though why this should be the case we do not know. After having suffered for some time, however, the bees barricade the entrance by building behind it a wall of wax and propolis, through which they make a hole large enough to admit themselves, but which quite excludes the bulky body of the moth. Here, too, we have reason and foresight in a high degree, as much, I think—perhaps more so—as has ever been observed in any occasional act of an ant, devised to meet special circumstances. For it is only in years in which the death’s-head moth is specially abundant that the bees act in this way; and, moreover, when it seems no longer required, they remove the barrier they have made.
The puzzling thing is that acts like this seem to show higher intelligence than, to judge by various experiments, one would think either ants or bees possessed. The results, for instance, of the experiments made by Lord Avebury in this direction, are rather disappointing than otherwise, especially with ants, creatures so far advanced in civilisation, as we may call it, and the ways of man, that they keep both cows and slaves, milking the one and making the others work for them. The cows are represented by little insects called aphides, one species of which we are accustomed to see upon our rose trees, andthe milk is a drop of nectar which they exude from the abdomen, upon the ants gently tapping them there with their antennæ. Various kinds of ants milk various kinds of aphides, and some keep them in their nests, where, indeed, they are born, their eggs being tended with the same care as those of the ants themselves. Thus we see amongst ants a creature kept and used regularly for a certain purpose, as domestic animals are amongst ourselves, and this, as far as we know, is unique in the animal world. The aphides, too, belong to a family of insects quite distinct from the Hymenoptera, amongst which the ants are included.
Ant-slaves, on the other hand, are ants themselves, though belonging to another species than their masters. The latter raid their nests and carry off, without injury, the larvæ and pupæ, which they afterwards hatch out in their own. These ants, therefore, are born into slavery, so that they do not know their condition, if we could suppose that that would disquiet them, and, moreover, they are not ill-used, but treated in every respect as well as though they belonged to the community in which they have been born. The only thing that makes them slaves is that they work for the ants by whom they have been captured, but this they docon amore—ants love working—so that there is no hardship in it. They work, however, in varying degrees, some species of slave-making ants being accustomed to do a certain amount for themselves, whilst others even require to be fed, and are often carried by their slaves, who, of course, do all the regular household business of building, feeding the young, bringingfood to the nest, etc., etc. When Huber—the great French observer of ants and bees—placed thirty of this latter kind of slave-making ants in a box, with some of their larvæ and pupæ and a supply of honey, but without any slaves, “more than one half of them died of hunger in less than two days.” The others were languid and without strength, and appeared able to do nothing. Commiserating their condition, Huber at length gave them a slave. “This individual, unassisted, established order, formed a chamber in the earth, gathered together the larvæ, extricated several young ants that were ready to quit the condition of pupæ, and preserved the life of the remaining Amazons,” as Huber calls these slave-raiders, in allusion to their sex. It is only the worker ants of any species who are taken away by others, whilst still immature, to be afterwards hatched out as slaves, for they alone would be of use. Both ants and bees, as is well known, are divided into three different sets or castes, the males, the perfect females, who become queens and are the founders of the community, and the immature females or workers, who are the most interesting of the three, and by whom the whole work of the hive or nest is carried on.
One of the most extraordinary of all ants—and therefore of all insects—is the honey-ant of Mexico (with some adjoining regions) and Australia. Amongst these, a certain section of the community take the place of aphidæ amongst other ants. They live but to distribute honey to the rest, and by reason of this, and the remarkable way in which their purpose is accomplished, may besaid to be living honey-pots. In the first place, they are themselves fed with honey by the workers, who swallow it and bring it up from their stomachs in the way in which a pigeon brings up food for its young—a process which is called “regurgitation.” During this process the abdomen of the honey-bearers begins to swell, and by degrees becomes quite globular, and of such a disproportionate size to the rest of the body that the latter projects from it like a piece of stick, and is raised high above the ground. When thus fully distended it is difficult for the insect to walk—a feat which it can only accomplish sideways—but it has, as a rule, no necessity to do so, and only clings motionless to the vaulted roof of the cell or chamber in which it is enclosed. This is of a roughly circular shape, about three inches across, and an inch or three-quarters of an inch in height. It is called the honey-chamber, and in it a number of these honey-bearers reside—if they may not rather be said to be stored—hanging closely together, and looking like a bunch of currants or small amber-coloured grapes—for their abdomens are transparent, so that the honey shows through them. It used to be thought that these ants had no stomachs, so that the abdomen itself made the jar for the honey. This, however, is a mistake. The honey on being swallowed, is received into the stomach, and this by swelling inordinately, causes the abdomen to swell too. It is interesting that whilst the floors of these honey-chambers are quite smooth, the roof is rough, so that the ants, fixing their feet upon the granulated surface, can cling there more securely. We need not suppose,however, that the ants produce this result purposely, for it is by their constantly walking over the floors of the chambers that they become smooth and polished. Here, then, we have the honey-jars. The workers when they are hungry come to them, and lifting their mouths up to the mouth of the jars, the honey from the latter is poured—or regurgitated—into them. In doing this the honey-bearing ant—or, as she is often called, from the shape of her abdomen, the rotund—throws her head up, and a drop of clear, amber fluid is then seen to exude from her mouth, which is eagerly licked up by the workers.
It is to be presumed that the latter crawl up the walls of the honey-chambers in order to be fed by the rotunds; but I am not quite sure whether Mr. MacCook, who kept these ants, and is the authority upon them, ever actually saw them do this. On the other hand, he often saw them fed upon the ground; but then, I think, he had put the honey-bearing ants there. In his book he gives some interesting illustrations of the feeding taking place. It used to be thought that these poor honey-pot ants were unable to walk, and lived all their lives in one place. This, however, is not the case. Mr. MacCook tells us that he has “frequently seen them coming out of their chambers, ascending the galleries, and moving freely about them.” They went sideways, and half slid and half crawled along. Again, when he placed them on a table, they were able to move “with no little agility.” If, however, they happened to fall from the roof where they were clinging, which sometimes they did through people shaking them, they were not able to get up again,but lay there helpless. It is not always, however, that these honey-jars are full, and when they are half or three-quarters empty they can walk very much better.
Some ants, it is now well known, are accustomed to store up grain in their nests during the summer or autumn, so as to have a supply of food during the winter. Long ago this habit had been recorded by Solomon, who says, “The ants are a people not strong, yet they prepare their meat in the summer”; and again, “Go to the ant, thou sluggard; consider her ways, and be wise: which having no guide, overseer, or ruler, provideth her meat in the summer, and gathereth her food in the harvest.” Classic writers have also dwelt upon this interesting point in ant economy, so that for a long time it was taken for granted not only that some ants stored grain, but that all of them did. However, when the European species began to be observed very carefully, this opinion was found to be erroneous, and Huber and other investigators, having convinced themselves that grain in these instances was not so stored, opinion began to go to the other extreme, and the fact was denied altogether. It was supposed that Solomon, and the ancient writers generally, had seen the ants carrying their little white larvæ or pupæ—as anyone may do who disturbs a nest—and that these had been mistaken for seeds.
For my part, I think that this is very likely to have been the case in some instances, for until lately it has not been the custom to watch insects, or indeed any animals, minutely, and it is not the business—and often not the interest—of poets to verify matters of this kind. In theMishna, however, which is a collection of old Jewish writings, we find a law relating to this grain stored up by the ants, and the ownership of it; and anyone who had read this might have known that the thing was a reality, since minute regulations about the possession of something can hardly exist, unless that something exists, too. This is the law, which, as will be seen, dealt fairly by everyone except by the ants—“The little caves of ants, when in the midst of a standing crop, are adjudged to the owner of the field; of those behind the reapers, the upper part is the property of the poor, the lower of the proprietor.” Rabbi Meir, however, decided that “all belong to the poor, since whatever is in doubt, in gleaning, goes to the gleaner.”
Yet in spite of the strong presumption in favour of ant providence and foresight, which this piece of ancient legislation raises, opinion was against it, and it was not till 1829 that the question was set at rest by Lieutenant-Colonel Sykes, who, whilst at Poonah, in India, saw and examined these “little caves of the ants” and also the ants carrying the seeds, not into but out of them. “Each ant,” he tells us, “was charged with a single seed; but, as it was too weighty for many of them, and as the strongest had some difficulty in scaling the perpendicular sides of the cylindrical hole leading to the nest below, many were the falls of the weaker ants with their burdens, from near the summit to the bottom.” The ants, however, that thus fell never relaxed their hold of the grain they were carrying, and, with a perseverance affording a useful lesson to humanity, “steadily recommencedthe ascent, after each successive tumble, nor halted in their labour until they had crowned the summit and lodged their burden on the common heap.” This observation was made just after the heavy rains of the Indian monsoon. The seeds had probably got wet, and the ants were bringing them up to dry in the sun.
Here then, at last, the truth of the ancient opinion as to ants storing grain was vindicated; but now came another and still more wonderful discovery. A harvesting ant—one, that is to say, that stored grain—was found to inhabit Texas, and Dr. Lincecum, who lived for twelve years in that country, came to the conclusion that this species not only stored the grain, but planted it, too, so as to have a crop of seeds next year, just as a farmer plants wheat. In an account of this ant which Dr. Lincecum sent to Darwin, who read it before the Linnean Society, he says: “The species which I have named Agricultural, is a large, brownish ant. It dwells in what may be termed paved cities, and like a thrifty, diligent, provident farmer, makes suitable and timely arrangements for the changing seasons. When it has selected a situation for its habitation, if on ordinary dry ground, it bores a hole, around which it raises the surface three and sometimes six inches, forming a low circular mound, having a very gentle inclination from the centre to the outer border, which on an average is three or four feet from the entrance. But if the location is chosen on low, flat, wet land, liable to inundation, though the ground may be perfectly dry at the time the ant sets to work, it nevertheless elevates the mound in the form of a pretty sharp cone to the heightof fifteen to twenty inches or more, and makes the entrance near the summit. Around the mound, in either case, the ant clears the ground of all obstructions, and levels and smooths the surface to the distance of three or four feet from the gate of the city, giving the space the appearance of a handsome pavement, as it really is. Within this paved area not a blade of any green thing is allowed to grow except a single species of grain-bearing grass. Having planted this crop in a circle around, and two or three feet from, the centre of the mound, the insect tends and cultivates it with constant care, cutting away all other grasses and weeds that may spring up amongst it, and all around, outside the farm-circle, to the extent of one or two feet more. The cultivated grass grows luxuriantly, and produces a heavy crop of small, white, flinty seeds, which under the microscope very closely resemble ordinary rice. When ripe it is carefully harvested and carried by the workers, chaff and all, into the granary cells, where it is divested of the chaff and packed away. The chaff is taken out and thrown beyond the limits of the paved area. During protracted wet weather,” continues Dr. Lincecum, thus supporting the observations of Lieutenant-Colonel Sykes, “it sometimes happens that the provision stores become damp, and are liable to sprout and spoil. In this case, on the first fine day, the ants bring out the damp and damaged grain and expose it to the sun till it is dry, when they carry it back and pack away all the sound seeds, leaving those that had sprouted to waste.”
In 1877 Mr. MacCook visited Texas on purpose to findout whether the harvesting ants really sowed the seed, as Dr. Lincecum had reported, for of course anyone may be mistaken. He saw a good deal of what Dr. Lincecum had seen, but not all, which is no wonder, since he only stayed a few weeks, whereas Dr. Lincecum had lived in the country for twelve years. Mr. MacCook could not make up his mind upon the subject, but he saw no reason why the ants should not sow their seed, nor has he given any better explanation of their clearing a space and not letting anything but their ant-rice grow upon it. There can, I think, be very little doubt that Dr. Lincecum was right in his opinion. We need have no difficulty in believing that some ants have fields and raise crops upon it, because there are other kinds, which, though they do not do this, do other things which are quite as wonderful, and demand quite as much intelligence. Mr. Belt, too, as we shall see, in a little, believes that some ants in South America grow mushrooms and make beds to grow them on.
This is the description which Mr. MacCook gives of the way in which a harvesting-ant carries its grain of rice—as big almost and heavy as itself—to the nest. “At last a satisfactory seed is found. It is simply lifted from the ground, or, as often happens, has to be pulled out of the soil, into which it has been slightly pressed by the rain or by passing feet. Now follows a movement which at first I thought to be a testing of the seed, and which, indeed, may be partially that; but finally I concluded that it was the adjusting of the burden for safe and convenient carriage. The ant pulls at the seed-husk with its mandibles,turning and pinching or feeling it on all sides. If this does not satisfy, and commonly it does not, the body is raised by stiffening out the legs, the abdomen is curved underneath, and the apex applied to the seed. I suppose this to be simply a mechanical action for the better adjusting of the load. Now the worker starts homeward. It has not lost itself in the mazes of the grass-forest. It turns directly towards the road (one of the little roads made by the ants, as they come and go to and from their nest) with an unerring judgment. There are many obstacles to overcome. Pebbles, pellets of earth, bits of wood, obtruding rootlets, or bent-down spears of grass block up or hinder the way. These were scarcely noticed when the ant was empty-handed. But they are troublesome barriers now that she is burdened with a seed quite as thick, twice as wide, and half as long as herself. It is most interesting to see the skill, strength, and rapidity with which the little harvester swings her treasure over or around, or pushes it beneath these obstacles. Now the seed has caught against the herbage as the porter dodges under a too narrow opening. She backs out and tries another passage. Now the sharp points of the husk are entangled in the grass. She jerks or pulls the burden loose, and hurries on. The road is reached, and progress is comparatively easy. Holding the grain in her mandibles well above the surface, she breaks into what I may describe with sufficient accuracy as a ‘trot,’ and with little further interruption reaches the disk (the cleared space round the nest, that is to say) and disappears within the gate.”
The seeds, when thus brought into the nest, are stored by the ants in long galleries, or in vaulted chambers, the floors of which have been specially prepared for its reception. It is a very curious thing that the stored seeds, though they often become quite moist, do not germinate, as would be the case under ordinary circumstances, if we, for instance, were to lay them in some cave or cellar. Were they to do so they would become bitter, and, of course, unfit for food, so that it seems as if the ants must have some way of stopping the process of nature. What this way is we do not know, but if, out of a great many thousands, some of the seeds do begin to sprout, the ants bite off the little rootlet or radicle that then makes its appearance, by which act the germination is prevented from going farther. It is quite as wonderful that the ants should have found out how to prevent the seeds from growing in their nests—and do it in two ways—as it is that they should plant it in fields specially prepared for it to grow upon.