CHAPTER XIV
Ant partnerships—How some ants feed—Persuasive methods—Animperium in imperio—Amusement by instinct—Begging the question—Nest within nest—Ant errors v. human perfection—Distorted arguments—How partnerships begin—Housing an enemy—Ant ogres.
THE relation of slave and slave-master—to use the received terminology—is not the only one of a social and friendly nature in which ants of different species stand towards one another; for as will have been gathered in the previous chapter, slavery amongst ants is a quite friendly institution, conducted, in fact, upon the “liberty-equality-fraternity” principle. Some species of ants, however, inhabit the nests of other species, or build their own amidst theirs in such a way as almost to make them one, and thus they live as perpetual guests, not only without paying for such accommodation by rendering their hosts any services, but often forcing these latter to be of service to them in other ways also. Thus, a small species of Texan ant whose first or Christian name isLeptothorax, but whose surname has not yet been fixed upon, lives on these terms in the nests of a larger one, the celebratedMyrmica brevinodis. Whether Professor Wheeler was the discoverer of the little ant I am not quite sure, but he was the first, I think, to observe its relations with the big one and those of the big one with it, and his accountof them is excessively interesting. “A small dish,” he says, “containing a syrup of sugar and water was placed near the nest (an artificial one under close observation). This was soon found by two of theMyrmicaworkers, which at once gorged themselves with the liquid and returned into the nest.”[56]Soon afterwards aLeptothoraxworker entered it also, and having run or tracked down one of the two honey-gorged creatures, forthwith got up on to its back, and, seated there, began to lick its head, an attention which it supplemented with a soft, persuasive titillation with its antennæ, whilst at the same time communicating a motion to its abdomen, which Professor Wheeler is so convinced must have been accompanied with certain sounds—known to the learned as stridulations—that he does not hesitate to affirm that it was thrown “into stridulatory oscillation.” Nor was theMyrmicadeaf to such an appeal. It slackened its pace, hesitated, then paused, and as though unable longer to resist the influence, folded its antennæ and appeared to give itself up to the full pleasure of the thing. The tempter, now, still making soft play with the antennæ, lowered its own head, and began to lick theMyrmicafirst on one cheek and then the other, including also the mandibles and parts adjoining. Thus fostered, a dewy moisture, drawn evidently from the reservoir of lately swallowed nectar, began to glisten on the lips of the large ant, and, increasing rapidly to a droplet, was re-imbibed by the expectant little one. “The latter,” says Professor Wheeler, “then dismounted, ran to anotherMyrmica, climbed on its back, and repeated the very same performance. Again it took toll, and passedon to still anotherMyrmica.”[56]Up to the present the attention of Professor Wheeler had been concentrated on the doings of this one individual, but now, turning his attention to other parts of the nest, he “observed that nearly all theLeptothoraxworkers were similarly employed. In one corner a number ofMyrmicaworkers had formed a circle about a few of their small larvæ, which they were cleansing and feeding. ALeptothoraxsoon found its way to this cluster, and stepped from the back of one ant to that of another, lavishing a shampoo on each in turn, and apparently filling its crop with the liquid contributions thus solicited.”
The above method of obtaining food appears to be peculiar to these ant parasites. Beetles, for example, solicit it either by taps or touches with the antennæ—which is a similar one indeed, but does not go so far nor involve a ride—or else by stroking the face of their host with their fore-feet. Other species of ants, when soliciting food from one another or demanding it from their slaves, employ a more or less similar method, whilst theLepismidthat we have before spoken of is a thief pure and simple. Licking seems to be the personal discovery ofLeptothorax, and being licked the peculiar privilege ofMyrmica brevinodis. That it is a valued one is clear, but the price asked for it is not always forthcoming, possibly because there is not always anything to forthcome. On such barren occasionsLeptothoraxmakes the best of a bad job, and dismounting from its first love, runs about looking for another.
Sometimes, after having licked the head and face of itspatron, the poor petitioner turns round and proceeds to do the same by its abdomen. This, perhaps, is a last effort of persuasion, but Professor Wheeler rather supposes the surface ofMyrmica’sbody to be “covered with some agreeable secretion.” QueenMyrmicas, however, seem to be very rarely treated to any sort of licking, and males apparently never. The reason of this, probably, is that both queens and males are themselves accustomed to receive their food from the workers by a similar process of regurgitation, and are probably therefore not in the habit of regurgitating it. They are therefore neglected by the little parasites, who console themselves by being all the more insistent with those who have something to give. These—that is to say, the workers—are waylaid whenever they enter the nest, as having presumably found something to eat outside it, and, in order to be on the spot, at once their importunate lickers, who seem to live in a perpetual state of crying, “Give! give!” keep in the more or less immediate proximity of the entrance, or entrances, should there be more than one. Professor Wheeler, indeed, doubts if theLeptosever feed themselves in the ordinary way, but inasmuch as they were on one occasion seen by him to do so, such doubt appears to me to be uncalled for.
These little ants make, in regard to the big ones within whose nest they live, a sort ofimperium in imperio. In a small chamber surrounded by the large galleries of theMyrmicas, and communicating with these by a passage too narrow for the latter to pass through, lives the queen with a small number of workers; eight of them in the nest observed by Professor Wheeler, together with a fewlarvæ, almost filling the cavity. They appear to be on affectionate terms with one another, the workers feeding their queen in the most assiduous manner, and she often playing with them like a cat with her kittens, throwing them on to their backs, and then “hugging and kissing them” (as Professor Wheeler describes it)con amore. Not that the Professor himself takes this view of it, for after hesitating whether to ascribe such behaviour to maternal affection, “the play instinct,” or hunger, he decides for the latter—on what grounds, since there was a continual passage of viands from one ant to another, the queen especially being “assiduously fed,” I am unable to see. What, too, is “the play instinct,” except a mere term made use of in order to suggest the idea of automatism in regard to an act which hardly seems to admit of such an interpretation? Instincts represent imperious necessities which, if not attended to, the species must fail or perish. Such, at any rate, are the grounds on which they must be supposed to have been originally built up. But what creature has had to play in order to survive? Not ants, surely, who work so hard that they cannot stand in need of more exercise than their daily life affords them. Nor, it would seem, is such an instinct developed amongst other insects, which again seems to show that it cannot be of any great importance. When, therefore, we find that ants, the most wonderful of all insects, do play, this strongly suggests their possession of an intelligence analogous to that of the higher animals. Instinct, however, is largely independent of intelligence, such as we understand it, and therefore, to allude to “the playinstinct” in ants before the instinctive character of the act has been made out, is to prejudge the question whether ants are automatic or reasoning beings.
The smallness of the passages leading from the interior chamber ofLeptothoraxto the broad galleries of theMyrmicassuggests that the latter were not intended to pass through them; but we cannot really draw this inference, since an ant in tunnelling would allow for the size of its own body, but not for that of another species. Certain it is that the big ants constantly force their way through the narrow passages, thus partly breaking down the wall, and that they are then received by the little ones in a quite friendly manner, and persuaded to part with some of their interior stores. Still, when this has been effected, their friends seem mildly desirous that they should go, and, as soon as they have gone, set to work to repair the breaches made by their entrance. No sooner has this been done, however, than they are broken down again, and so it may continue, apparently, for an indefinite period, at any rate in nests constructed for observational purposes, and where the conditions are, therefore, more or less artificial. Whether it is so to anything like the same extent under nature may well be doubted, for that any creature should live in a state of never-ending useless labour does not seem likely; and, moreover, unless the one ant could have made itself comfortable within the nest of the other, why should it have become established there at all? But whatever it may be outside the study, this is Professor Wheeler’s account of what fell under his observation: “At one p.m.,” he tells us, “theMyrmicaworkers discovered thehiding-place of their little companions, and two of them, in single file, shouldered their way through the narrow passage, enlarging it as they proceeded. As soon as the head of the firstMyrmicaappeared in the chamber, theLeptothoraxeswhich had been attending to their morning toilet and that of their larvæ, and to the careful arrangement of their eggs, turned to meet the intruders.”
“Now dreadful deedsMight have ensued,”
“Now dreadful deedsMight have ensued,”
“Now dreadful deedsMight have ensued,”
“Now dreadful deeds
Might have ensued,”
and for such an upshot, indeed, upon the first occasion, Professor Wheeler was prepared. “For an instant,” he says, “I fully expected to see a fierce battle, but I had misjudged theLeptothoraxcharacter. To my surprise theMyrmicason entering were received with a profusion of shampooing, and, though sadly crowding the occupants of the little chamber, they let themselves down comfortably, and appeared to experience all the sensuous satisfaction of a couple ofrouéswho have dropped into a Turkish bath for the night. Yet the littleLeptos, though behaving in this friendly manner” (their conduct indeed was not more disinterested than upon other occasions), “seemed to have some dim desire to remove theMyrmicasfrom their nest, for from time to time one was seen to pull with her mandibles at the fore leg or antenna of one of the intruders, as if to remind her that there are limits to polite hospitality.” Professor Wheeler adds that “this was the only act even approaching hostility witnessed between the two species. TheMyrmicasnever showed the slightest irritation towards theLeptos, never seized them in their mandibles or even menaced them. They seemedrather to look upon the little creatures with gentle benevolence, much as human adults regard little children. They never passed their little guests without the antennal greeting, and theLeptosshampooed their hosts with comical zeal.”[56]The continued breaking down and repair of the dividing wall is then described, with the conclusion that “in their natural environment theLeptothoraxeswould not be cramped for space, and would probably dig their cell where they would not so frequently be disturbed by their inquisitive hosts.”
As regards the possible effects upon theMyrmicasof having thus frequently to render up food swallowed for their own nourishment, it must be remembered that amongst most ants this is a thing of custom; and, again, it seems probable that there would be an internal sense on the part of the regurgitating individual as to concessions of this nature having gone as far as it was healthy that they should go. As we have seen, they are not infrequently refused. Professor Wheeler, however, came to the conclusion thatMyrmicacolonies suffer very considerably from this cause, and on this he makes the following comment: “If I have correctly estimated the influences which may tend to diminish the fecundity and prosperity of theMyrmicas, we have in this double nest another striking demonstration of the complete absence in ants of any faculty of reason. For if theMyrmicaspossessed a glimmer of this faculty they could easily annihilate the gluttonous little nest-mates that are for ever roaming about their galleries like so many animated stomach-pumps.”[56]Yes, truly amost“striking demonstration,”seeing that we human ants can annihilate, all in a moment, any evil that has insensibly gained a footing amongst us, and with which we have been familiarised from birth. Custom, growing gradually from unnoticed beginnings, plays no part at all amongst us—never affects our views in the very slightest degree. In Europe we hang up all the brewers and distillers; whilst mobs of infuriated Chinamen rend in pieces the vendors of opium and crushers of their women’s feet. There is no such thing inhumannature as tolerating an evil for the pleasure that lives in it; nomanruins his health, and sinks into an early grave, through being a slave to sensual pleasures. Nor can what is manifestly wrong seem right tous; there is no pernicious, obstinate, wilful shutting ofoureyes. What a contrast does all this present with such a state of affairs as we are here considering! And how plain it is that there can be no reasoning power in the ant, since reason and right conduct are synonymous with man!
What is the origin of these strange co-partnerships—for there are others—which we find existing between ants of two different species living in the same or in one double nest? As we know, the different species of ants are commonly very hostile to one another; and for any to enter the nest of some other one is to court destruction, if they be not the stronger party. Nay, they dare not even enter a strange nest of their own species. It seems probable, therefore—this, at least, is my own view of it—that such friendly cohabitation has come about through the channel, not of peace, but of war—throughsuccessful encroachments which, from being unavoidable, have come gradually to be less and less resented, till the two parties, mingling freely, have learnt to live on other terms. Now there are ants which live, like ogres, in the nests of other species, preying upon their eggs and young. Such a one isSolenopsis fugax—to whom we will come presently—but it is perhaps even more interesting to find in species between whom relations of a similar nature to those which we have been considering exist, occasional slight traces of a mutual hostility. As between theLeptosandMyrmicasindeed this has only as yet been noticed, very faintly, on the part of the former; but in regard to another pair who live together—our great wood-ant, namely,Formica rufaand tiny littleFormicoxenus nitidulus—Professor Wheeler remarks: “On one occasion in one of my artificial nests, in which the ants had previously lived on good terms with one another, I saw aFormicatouching aFormicoxenuswith her antennæ and menacing her with her mandibles, but she departed without even attempting to seize her. In the same nest I found aFormicoxenuswhich had seized the leg of aFormicain its mandibles and had died in this position.”[57]Other observers, too, have from time to time—but only very occasionally—noticed facts of the same sort. Through such exceptional slight indications we may perhaps see, “as in a glass darkly,” what things were at the beginning.
Let us now look at the beginning.Solenopsis fugax, Sir John Lubbock tells us, “makes its chambers and galleries in the walls of the nests of larger species, andis the bitter enemy of its hosts. The latter cannot get at them because they are too large to enter the galleries. The littleSolenopses, therefore, are quite safe, and, as it appears, make incursions into the nurseries of the larger ant and carry off the larvæ as food. It is as if we had small dwarfs about eighteen inches to two feet long harbouring in the walls of our houses and every now and then carrying off some of our children into their horrid dens.”[58]This is the general proposition. Monsieur Janet can add a few particulars. “TheSolenopsis,” he says, “may establish itself near almost any other ants of our country, and is found especially with....” Here follows a list all in Latin, but our common Wood-ant—the large one that makes those great heaps of pine-needles—and the Amazon, or slave-making ant, are contained in it.[59]“TheSolenopsisnest,” continues M. Janet, “may partially surround that of its neighbour’s, or it may even be partly excavated in the masses of earth which separate the galleries of the latter. In each case—and probably, too, when, as is frequent, there is not such close contiguity—fine connecting galleries enable theSolenopsisto make incursions into the nests of their neighbours, where, as we shall see, they find an abundance of food. The actual nest consists of a number of small circular chambers about 8-20 mm. in diameter and only 6-8 mm. in height. Most of these chambers are separated from one another by several centimetres, and are connected by slender galleries, often less than two millimetres in diameter, entering the chambers at their walls, ceilings, or floors, which latter are remarkably clean, smooth, and hard.”[59]
The food of which these horrid little ants find such an abundance is, of course, the cocoons and larvæ of their unfortunate neighbours, and M. Janet gives the following account of the way in which they dispose of them: “From ten to thirty of them,” he says, “climb up on to a cocoon and cover it with little perforations which, finally, becoming confluent, enable them to reach its contents. If it contains a pupa, the legs and antennæ fall an easy prey to the mandibles of theSolenopses. In this case the victim is cut into, sucked, and torn into very small pieces, which the ants hasten to carry away into the interior of the nest. The operation is much more difficult in the case of a larva which has just spun its cocoon. Such a one I have seen theSolenopsesdrag into the interior of the nest and keep working at for twenty-four hours. At the expiration of this period the larva began to look flaccid (as may be believed), and was covered with little black dots which were, sometimes, double, corresponding with the little wounds made by the mandibles of its assassins. Numbers of the latter were busy lapping up the liquid which exuded from the wounds, but it was not until thirty-six hours had elapsed that the larva was entirely devoured.”[59]This is certainly not a pleasant picture, yet, if our surmise is correct, the remote descendants of these murderousSolenopsesmay become as harmless and as pretty in their ways as the littleLeptos, a reflection which goes far to discount any uncomfortable feelings we might otherwise have been inclined to have in regard to the general plan or scheme of things. Thus, in nature, though occasionally a slightshadow may seem to rest upon the landscape, the next moment the very memory of it is lost in a blaze of sunlight glory.
Forel believes that when aSolenopsis, and one of the larger species of ants that it plagues, meet, the latter are unable to see it on account of its small size, so that, practically, it is invisible. This seems a strange doctrine, since the same ants can see smaller things; and yet, from their behaviour under such circumstances, M. Janet is inclined to think so too. It can hardly be that they shun combat, though theSolenopses, in spite of their small size, are able, even here, by virtue of their numbers, and being armed with stings, to meet their victims, as one may almost call them, upon equal terms. M. Janet, indeed, once saw so strong and warlike a species as the slave-makingFormica sanguineakilled by some half-dozenSolenopses, but he adds that on such occasions a considerable number of the latter were, generally, killed also. This, however, is not sufficient to abate the evil, so perhaps the molested species, finding that fighting is of no use, accustomed to seeSolenopsesfrom their birth, recognising, too, as a part of their own atmosphere, the distinctive smell which they, no doubt, possess, accept them like some disagreeable part of their lives, and try to make the best of it.