He afterwards appeals to nature, and calls upon all who doubt to repeat his experiments, which he is sure will soon satisfy them:—a satisfaction which, as I have just observed, in this country we cannot receive, for want of the slave-making species.—And now to begin my history.
There are two species of ants which engage in these excursions, Polyergus rufescens and Formica sanguinea: but they do not, like the African kings, make slaves of adults, their sole object being to carry off the helpless infants of the colony which they attack, the larvæ and pupæ; these they educate in their own nests, till they arrive at their perfect state, when they undertake all the business of the society[83]. In the following account I shall chiefly confine myself to what Huber relates of the first of these species, and conclude my extracts with his history of an expedition of the latter to procure slaves.
The rufescent ants[84] do not leave their nests to go upon these expeditions, which last about ten weeks, till the males are ready to emerge into the perfect state: and it is very remarkable, that if any individuals attempt to stray abroad earlier, they are detained by their slaves, who will not suffer them to proceed. A wonderful provision of the Creator to prevent the black colonies from being pillaged when they contain only male and female brood, which would be their total destruction, without being any benefit to their assailants, to whom neuters alone are useful.
Their time of sallying forth is from two in the afternoon till five, but more generally a little before five: the weather, however, must be fine, and the thermometer must stand at above 36° in the shade. Previously to marching there is reason to think that they send out scouts to explore the vicinity; upon whose return they emerge from their subterranean city, directing their course to the quarter from which the scouts came. They have various preparatory signals, such as pushing each other with the mandibles or forehead, or playing with the antennæ, the object of which is probably to excite their martial ardour, to give the word for marching, or to indicate the route they are to take. The advanced guard usually consists of eight or ten ants; but no sooner do these get beyond the rest, than they move back, wheeling round in a semicircle, and mixing with the main body, while others succeed to their station. They have "no captain, overseer, or ruler," as Solomon observes, their army being composed entirely of neuters, without a single female: thus all in their turns take their place at the head, and then retreating towards the rear, make room for others. This is the usual order of their march; and the object of it may be to communicate intelligence more readily from one part of the column to another.
When winding through the grass of a meadow they have proceeded to thirty feet or more from their own habitation, they disperse; and, like dogs with their noses, explore the ground with their antennæ to detect the traces of the game they are pursuing. The negro formicary, the object of their search, is soon discovered; some of the inhabitants are usually keeping guard at the avenues, which dart upon the foremost of their assailants with inconceivable fury. The alarm increasing, crowds of its swarthy inhabitants rush forth from every apartment; but their valour is exerted in vain; for the besiegers, precipitating themselves upon them, by the ardour of their attack compel them to retreat within, and seek shelter in the lowest story; great numbers entering with them at the gates, while others with their mandibles make a breach in the walls, through which the victorious army marches into the besieged city. In a few minutes, by the same passages, they as hastily evacuate it, each carrying off in its mouth a larva or pupa which it has seized in spite of its unhappy guardians. On their return home with their spoil, they pursue exactly the route by which they went to the attack. Their success on these expeditions is rather the result of their impetuosity, by which they damp the courage of the negroes, than of their superior strength, though they are a larger animal; for sometimes a very small body of them, not more than 150, has been known to succeed in their attack and to carry off their booty[85].
When from their proximity they are more readily to be come at than those of the negroes, they sometimes assault with the same view the nest of another species of ant, which I shall call the miners (F. cunicularia). This species being more courageous than the other, on this account the rufescent host marches to the attack in closer order than usual, moving with astonishing rapidity. As soon as they begin to enter their habitation, myriads of the miners rushing out fall upon them with great fury; while others, well aware of their purpose, making a passage through the midst of them, carry off in their mouth the larvæ and pupæ. The surface of the nest thus becomes the scene of an obstinate conflict, and the assailants are often deprived of the prey which they had seized. The miners dart upon them, fight them foot to foot, dispute every inch of their territory, and defend their progeny with unexampled courage and rage. When the rufescents, laden with pillage, retire, they do it in close order—a precaution highly necessary, since their valiant enemies, pursuing them, impede their progress for a considerable distance from their residence.
During these combats the pillaged ant-hill presents in miniature the spectacle of a besieged city; hundreds of its inhabitants may be seen making their escape, and carrying off in different directions, to a place of security, some the young brood, and others their females that are newly excluded: but when the danger is wholly passed, they bring them back to their city, the gates of which they barricade, and remain in great numbers near them to guard the entrance.
Formica sanguinea, as I observed above, is another of the slave-making ants; and its proceedings merit separate notice, since they differ considerably from those of the rufescents. They construct their nests under hedges of a southern aspect, and likewise attack the hills both of the negroes and miners. On the 15th of July, at ten in the morning, Huber observed a small band of these ants sallying forth from their formicary, and marching rapidly to a neighbouring nest of negroes, around which it dispersed. The inhabitants, rushing out in crowds, attacked them and took several prisoners: those that escaped advanced no further, but appeared to wait for succours; small brigades kept frequently arriving to reinforce them, which emboldened them to approach nearer to the city they had blockaded; upon this their anxiety to send couriers to their own nest seemed to increase: these spreading a general alarm, a large reinforcement immediately set out to join the besieging army; yet even then they did not begin the battle. Almost all the negroes, coming out of their fortress, formed themselves in a body about two feet square in front of it, and there expected the enemy. Frequent skirmishes were the prelude to the main conflict, which was begun by the negroes. Long before success appeared dubious they carried off their pupæ, and heaped them up at the entrance to their nest, on the side opposite to that on which the enemy approached. The young females also fled to the same quarter. The sanguine ants at length rush upon the negroes, and attacking them on all sides, after a stout resistance the latter, renouncing all defence, endeavour to make off to a distance with the pupæ they have heaped up:—the host of assailants pursues, and strives to force from them these objects of their care. Many also enter the formicary, and begin to carry off the young brood that are left in it. A continued chain of ants engaged in this employment extends from nest to nest, and the day and part of the night pass before all is finished. A garrison being left in the captured city, on the following morning the business of transporting the brood is renewed. It often happens (for this species of ant loves to change its habitation) that the conquerors emigrate with all their family to the acquisition which their valour has gained. All the incursions of F. sanguinea take place in the space of a month, and they make only five or six in the year. They will sometimes travel 150 paces to attack a negro colony.