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ants (Myrmica ruginodis) under observation in a glass vessel, and have frequently witnessed their conflicts. Introducing some individuals of the same species but from a different nest, we soon see numbers to engage generally in single combat. The ants seem to recognise each other and to distinguish friend from foe by crossing their antennæ ; that done, if friends meet, they pass on; if enemies, immediately the fight begins. We have over and over again witnessed that kind
of combat, which Forel designates combats à froid, or combats chroniques.
These combats,' he says, 'almost always begin by what I shall call pullings (tiraillements); the ants seize themselves by the feet or by the antennæ, and pull themselves without violence, without great efforts, but with a wonderful tenacity; they keep continually touching each other with their antennæ. In this case the two adversaries never pour poison over each other nor bend their abdomens. Nearly always one of the adversaries is patient, the other active; the first, without defending itself, submits with a stoical resignation; the other acts almost as the Indians do to their prisoners; it seizes an antenna of its victim, and endeavours, with a coolness truly infernal (avec une tranquillité vraiment infernale) to cut it, or rather to saw it off with its mandibles; that done, it cuts off a leg, or the other antenna, one after another, until its victim, frightfully mutilated but quite alive, is utterly unable to defend itself or even to guide itself; then it sometimes makes an end of it by cutting off its neck or thorax, but generally it drags it off and places it in some lonely spot, where it necessarily perishes. Not once only, but more than a hundred times, I have made this sad observation. A less unpleasant modification of this act takes place when the stronger ant, wishing simply to disengage itself from the other, without doing it harm, carries it as far as possible and leaves it, and hastens to return.' (Forel, p. 247.)
M. Forel has recorded a great many kinds of battles ; sometimes they take place between ants of different species or between those of different genera, or those of the same species, but of different ant-hills. It is most extraordinary how in this latter case the ants can distinguish between friend and enemy. One day we placed a number of ants (F. fusca) with their cocoons in a glass vessel with a number of Myrmica ruginodis. The latter attacked fusca most vigorously, which ran up the sides of the glass trying to escape; on examining the lot a few days afterwards, we saw several dead neuters, but not a vestige of their cocoons, which had doubtless been devoured by the stronger or more valiant enemy. Space forbids us to do more than give Huber's description of a fight between regular armies, the occupants of two large ant-hills of the same species (F. rufa), alike in their extent and population, situated about a hundred paces from each other.
VOL. CXLV. NO. CCXCVII.
Let us figure to ourselves this prodigious crowd of insects covering the ground lying between these two ant-hills, and occupying a space of two feet in breadth. Both armies met at half-way from their respective habitations, and there the battle commenced. Thousands of ants took their station upon the highest ground and fought in pairs, keeping firm hold of their antagonist by their mandibles; a considerable number were engaged in the attack and leading away prisoners. The latter made several ineffectual efforts to escape, as if aware that upon their arrival at the camp they would experience a cruel death. The scene of warfare occupied a space of about three feet square; a penetrating odour exhaled from all sides, numbers of dead ants were seen covered with venom. Those ants composing groups and chains took hold of each other's legs and pincers and dragged their antagonists on the ground. These groups formed successively. The fight usually commenced between two ants, who seized each other by the mandibles and raised themselves upon their hind legs, to allow of their bringing their abdomen forward and spurting the venom upon their adversary. They were frequently so closely wedged together that they fell upon their sides and fought a long time in the dust; they shortly after raised themselves, when each began dragging his enemy, but when the force was equal the wrestlers remained immovable and fixed each other to the ground, until a third came to decide the contest. It more commonly happened that both ants received assistance at the same time, when the whole four, keeping firm hold of a foot or antenna, made ineffectual attempts to gain the battle. Some ants joined the latter, and these were, in their turn, seized by new arrivals. It was in this way they formed chains of six, eight, or ten ants, all firmly locked together; the equilibrium was only broken when several warriors from the same republic advanced at the same time, who compelled those that were enchained to let go their hold, when the single combats again took place. On the approach of night each party returned gradually to the city which served it for an asylum. The ants which were either killed or led away captive, not being replaced by others, the number of combatants diminished until their force were exhausted.' (P. 189.)
Connected with their wars is the very remarkable instinct which leads certain species of ants to capture slaves and appropriate their labours for the duties of their own nests. Pierre Huber was the first to discover this in the case of Polyerges rufescens, a species which, strange to say, is absolutely dependent upon captured neuters of another species for their means of living. The labours of the neuters of Polyerges are strictly confined to slave-capturing ; they are incapable from long disuse of doing any other work; they cannot make their own nests, nor feed their larvæ. Huber has shown by an experiment how entirely dependent upon other ants are the neuters of this species, both for nourishment and habitation.
'I enclosed,' he says, 'thirty of these ants with several pupe and larvæ of their own species, and twenty pupæ belonging to the negroes (F. fusca), in a glass box, the bottom of which was covered with a thick layer of earth. I placed a little honey in their corner of the prison and cut off all association with their assailants. At first they appeared to pay some little attention to the larvæ; they carried them here and there, but presently replaced them. More than one half of the Amazons (Polyerges rufescens) died of hunger in less than two days. They had not even traced out a dwelling, and the few ants in existence were languid and without strength. I commiserated their condition and gave them one of their black companions. 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 pupe, and preserved the life of the remaining Amazons.'
The military expeditions for the purpose of capturing slaves of Polyerges rufescens have been well described by Huber and Ebrard, if we except a few errors which Forel has corrected. About the middle of the summer on fine days, from two to five hours after noon, is the best time of witnessing an expedition. At first, there is a continual running to and fro on the top of the nest; then, on a given signal, which they give by striking themselves mutually on the forehead, they start off, not all the inhabitants of the ant-hill, however, for a number always remain at home, but only a part of the militia of the state; the forces vary from a hundred to two thousand soldiers; they march in close ranks; those in front of the column wheel about, and turning back strike the foreheads of all those they meet, till they find themselves at the rear of the army; they in turn are followed by those who now march in front, thus the first become last, the first ranks being continually renewed. What can be the meaning of these repeated signals and interchange of movements ? Is it that the ants in the first ranks wish to assure themselves that they are followed by the rest; and are these tappings on the forehead intended as mutual encouragements ? Notwithstanding the delay caused by these undulatory movements, the march of the army is very rapid, especially in warm weather on level ground where there is no grass, leaves, or other obstacles. Now they halt for rest or consultation, now they form small detachments for exploration; then again form themselves into marching order; when they meet with an ant-hill of the F. fusca, they throw themselves upon it, invade the gates and enter the galleries, pillage the nest, running off each one with a cocoon in its mouth, and return home. If the spoil of the conquered city is abundant, they place the cocoons at the entrance of their own galleries in small packets, and return for further pillage.
The besieged ants seldom show much fight, and little blood is shed; for the invading host is composed of stout and fierce soldiers, and their military organisation is complete, while those attacked are small and undisciplined. Sometimes these last will pursue the rear-guard of their enemies, in hopes of recovering a few cocoons, but they seldom succeed; the pillagers do not take the trouble to kill them; they appear to add insult to injury, for they show their teeth, and the others, knowing what that means, run away home.
This interesting slave-making ant is not found in England; we have, however, a British species, the Formica sanguinea, which plunders the nests of other ants, carrying off their cocoons and making slaves * of the developed nymphæ. It is said to be plentiful in some localities, but is certainly not common. The worker major is three or four lines in length, with a blood-red head and thorax, and a black abdomen ; the worker minor is more fuscous than red; this ant makes its galleries in banks; the large workers or soldiers are a bold and a furious race; they capture the cocoons of F. fusca, F. cunicularia, and F. flava. " It was Huber who first showed that sanguinea was a slave-making ant, and his account has been verified by other observers; amongst them, our own illustrious Darwin.
* Although fully trusting,' Mr. Darwin says, 'to the statements of Huber and Mr. Smith, I tried to approach the subject in a sceptical frame of mind, as anyone may well be
excused for doubting the truth of so extraordinary and odious • an instinct as making slaves.' But these slaves, it appears, are not submitted to any cruel bondage. Mr. Darwin examined fourteen nests and found a few slaves of F. fusca, the negroes 'as Huber calls them, for they are black and not more than half the size of their red masters; it is only the workers of F. fusca that are found in the nests of sanguinea, the males and females occurring in their own ant-hills. But how do we know that the slaves are happy and contented in confinement? They will come out of the nest if it has been disturbed, and in common with their masters, fight in defence of their community, and will seize and carry away the exposed larvæ and nymphæ. These nests have been watched by Mr. F. Smith at various times in the months of May, June, and August, both in Surrey and Hampshire, and the slaves though present
* We have employed the usual expression of slave-making'ants ; perhaps kidnapping' is a more appropriate term; it is the baby-and in many cases cradle as well—that is stolen.
in large numbers were never seen by him to enter or leave the nest. Hence they are strictly household slaves. Mr. Darwin, however, tells us that he once noticed a few slaves mingled with their masters leaving their nest and marching to a tall Scotch fir-tree twenty-five yards distant, probably in search of aphides or cocci. In Switzerland, the negro-slaves do not confine their attention to household duties to the same extent as in this country; there the principal part of their labour consists in searching for aphides, in closing the doors of their galleries in the evening, and opening them in the morning; for in these species, particular care is taken to close every ' evening all the avenues, by blocking them up with whatever * materials they find proper for the purpose.'
M. Forel, speaking of F. fusca, tells us it is a timid species and the one that is most frequently made to work as a slave. We have already seen that when invaded by Polyerges rufescens, this little ant was easily subdued. In their battles with F. sanguinea, however, Mr. Darwin tells us they sometimes get the best of it.
One day I fortunately witnessed a migration of F. sanguinea from one nest to another, and it was a most interesting spectacle to behold the masters carefully carrying (instead of being carried by, as in the case of F. rufescens), their slaves in their jaws. Another day of attention I was struck by about a score of the slave-makers haunting the same spot, and evidently not in search of food; they approached and were vigorously repulsed by an independent community of the slave species (F. fusca); sometimes as many as three of these ants clinging to the legs of the slave-making F sanguinea. The latter ruthlessly killed their small opponents, and carried their dead bodies as food to their nest, twenty-nine yards distant; but they were prevented from getting any pupæ to rear as slaves. I then dug up a small parcel of the pupæ of F. fusca from another nest, and put them down on a bare spot near the place of combat; they were eagerly seized and carried off by the tyrants, who perhaps fancied that after all they had been victorious in the late combat.' (Origin of Species, p. 221,
There is a small but courageous little yellow ant (F. flava), which is occasionally made into a slave: Mr. Darwin placed some cocoons of this species with the slave-making F. sanguinea, curious to see whether they could distinguish them from those of F. fusca ; they were able to distinguish between them, for when they came across the cocoons of the little savage yellow ant, they were much terrified' and ran away ; but in about a quarter of an hour, shortly after all the little yellow ants had crawled away, they took heart and carried off “the pupæ.' Mr. Darwin contrasts the instinctive habits of