After their annual labours are begun, few are ignorant how incessantly ants are engaged in building or repairing their habitations, in collecting provisions, and in the care of their young brood; but scarcely any are aware of the extent to which their activity is carried, and that their labours are going on even in the night.—Yet this is a certain fact.—Long ago Aristotle affirmed that ants worked in the night when the moon was at the full[95]; and their historian Gould observes, "that they even exceed the painful industrious bees. For the ants employ each moment, by day and night, almost without intermission, unless hindered by excessive rains[96]." M. Huber also, speaking of a mason-ant, not found with us, tells us that they work after sun-set, and in the night[97]. To these I can add some observations of my own, which fully confirm these accounts. My first were made at nine o'clock at night, when I found the inhabitants of a nest of the red ant (Myrmica rubra) very busily employed; I repeated the observation, which I could conveniently do, the nest being in my garden, at various times from that hour till twelve, and always found some going and coming, even while a heavy rain was falling. Having in the day noticed some Aphides upon a thistle, I examined it again in the night, at about eleven o'clock, and found my ants busy milking their cows, which did not for the sake of repose intermit their suction. At the same hour, another night, I observed the little negro ant (F. fusca) engaged in the same employment upon an elder. About two miles from my residence was a nest of Gould's hill-ant (F. rufa), which, according to M. Huber, shut their gates, or rather barricade them, every night, and remain at home[98]. Being desirous of ascertaining the accuracy of his statement, early in October, about two o'clock one morning, I visited this nest in company with an intelligent friend; and to our surprise and admiration we found our ants at work, some being engaged in carrying their usual burthen, sticks and straws, into their habitation, others going out from it, and several were climbing the neighbouring oaks, doubtless to milk their Aphides. The number of comers and goers at that hour, however, was nothing compared with the myriads that may always be seen on these nests during the day. It so happened that our visit was paid while the moon was near the full; so that whether this species is equally vigilant and active in the absence of that luminary yet remains uncertain. Perhaps this circumstance might reconcile Huber's observation with ours, and confirm the accuracy of Aristotle's statement before quoted. To the red ant, indeed, it is perfectly indifferent whether the moon shine or not; they are always busy, though not in such numbers as during the day. It is probable that these creatures take their repose at all hours indifferently; for it cannot be supposed that they are employed day and night without rest.
I have related to you in this and former letters most of the works and employments of ants, but as yet I have given you no account of their roads and track-ways.—Don't be alarmed, and imagine I am going to repeat to you the fable of the ancients, that they wear a path in the stones[99]; for I suppose you will scarcely be brought to believe that, as Hannibal cut a way for the passage of his army over the Alps by means of vinegar, so the ants may with equal effect employ the formic acid: but more species than one do really form roads which lead from their formicaries into the adjoining country. Gould, speaking of his jet-ant (F. fuliginosa), says that they make several main track-ways, (streets he calls them,) with smaller paths striking off from them, extending sometimes to the distance of forty feet from their nest, and leading to those spots in which they collect their provisions; that upon these roads they always travel, and are very careful to remove from them bits of sticks, straw, or anything that may impede their progress; nay, that they even keep low the herbs and grass which grow in them, by constantly biting them off[100], so that they may be said to mow their walks. But the best constructors of roads are the hill-ants (F. rufa). Of these De Geer says, "When you keep yourself still, without making any noise, in the woods peopled with these ants, you may hear them very distinctly walking over the dry leaves which are dispersed upon the soil, the claws of their feet producing a slight sound when they lay hold of them. They make in the ground broad paths, well beaten, which may be readily distinguished, and which are formed by the going and coming of innumerable ants, whose custom it is always to travel in the same route[101]." From Huber we further learn, that these roads of the hill-ants are sometimes a hundred feet in length, and several inches wide; and that they are not formed merely by the tread of these creatures, but hollowed out by their labour[102]. Virgil alludes to their tracks in the following animated lines, which, though not altogether correct, are very beautiful:
"So when the pismires, an industrious train,
Embodied rob some golden heap of grain,
Studious ere stormy winter frowns to lay
Safe in their darksome cells the treasured prey;
In one long track the dusky legions lead
Their prize in triumph through the verdant mead;
Here bending with the load, a panting throng
With force conjoin'd heave some huge grain along;
Some lash the stragglers to the task assign'd,
Some to their ranks the bands that lag behind:
They crowd the peopled path in thick array,
Glow at the work, and darken all the way."
Bonnet, observing that ants always keep the same track both in going from and returning to their nest, imagines that their paths are imbued with the strong scent of the formic acid, which serves to direct them; but, as Huber remarks, though this may be of some use to them, their other senses must be equally employed, since it is evident, when they have made any discovery of agreeable food, that they possess the means of directing their companions to it, though it is scarcely possible that the path can have been sufficiently impregnated with the acid for them to trace their way to it by scent. Indeed the recruiting system described above, proves that it requires some pains to instruct ants in the way from an old to a new nest; whereas, were they directed by scent, after a sufficient number had passed to and fro to imbue the path with the acid, there would be no occasion for further deportations[103].
Though ants have no mechanical inventions to diminish the quantum of labour, yet by numbers, strength, and perseverance they effect what at first sight seems quite beyond their powers. Their strength is wonderful: I once, as I formerly observed, saw two or three of them haling along a young snake not dead, which was of the thickness of a goose-quill[104]. St. Pierre relates, that he was highly amused with seeing a number of ants carrying off a Patagonian centipede. They had seized it by all its legs, and bore it along as workmen do a large piece of timber[105]. The Mahometans hold, as Thevenot relates, that one of the animals in Paradise is Solomon's ant, which, when all creatures in obedience to him brought him presents, dragged before him a locust, and was therefore preferred before all others, because it had brought a creature so much bigger than itself. They sometimes, indeed, aim at things beyond their strength; but if they make their attack, they pertinaciously persist in it though at the expense of their lives. I have in my cabinet a specimen of Colliuris longicollis, Latr., to one of the legs of which a small ant, scarcely a thirtieth part of its bulk, is fixed by its jaws. It had probably the audacity to attack this giant, compared with itself, and obstinately refusing to let go its hold was starved to death[106]. Professor Afzelius once related to me some particulars with respect to a species of ant in Sierra Leone, which proves the same point. He says that they march in columns that exceed all powers of numeration, and always pursue a straight course, from which nothing can cause them to deviate: if they come to a house or other building, they storm or undermine it; if a river comes across them, though millions perish in the attempt, they endeavour to swim over it.
This quality of perseverance in ants on one occasion led to very important results, which affected a large portion of this habitable globe; for the celebrated conqueror Timour, being once forced to take shelter from his enemies in a ruined building, where he sat alone many hours, desirous of diverting his mind from his hopeless condition, he fixed his observation upon an ant that was carrying a grain of corn (probably a pupa) larger than itself up a high wall. Numbering the efforts that it made to accomplish this object, he found that the grain fell sixty-nine times to the ground, but the seventieth time it reached the top of the wall. "This sight (said Timour) gave me courage at the moment; and I have never forgotten the lesson it conveyed[107]."
Madame Merian, in her Surinam Insects, speaking of the large-headed ant (Œcodoma cephalotes), affirms that, if they wish to emigrate, they will construct a living bridge in this manner:—One individual first fixes itself to a piece of wood by means of its jaws, and remains stationary; with this a second connects itself; a third takes hold of the second, and a fourth of the third, and so on, till a long connected line is formed fastened at one extremity, which floats exposed to the wind, till the other end is blown over so as to fix itself to the opposite side of the stream, when the rest of the colony pass over upon it, as a bridge[108]. This is the process, as far as I can collect it from her imperfect account:—as she is not always very correct in her statements, I regarded this as altogether fabulous, till I met with the following history of a similar proceeding in De Azara, which induces me to give more credit to it.
He tells us, that in low districts in South America, that are exposed to inundations, conical hills of earth may be observed, about three feet high, and very near to each other, which are inhabited by a little black ant. When an inundation takes place, they are heaped together out of the nest into a circular mass, about a foot in diameter and four fingers in depth. Thus they remain floating upon the water while the inundation continues. One of the sides of the mass which they form is attached to some sprig of grass, or piece of wood; and when the waters are retired, they return to their habitation. When they wish to pass from one plant to another, they may often be seen formed into a bridge, of two palms length, and of the breadth of a finger, which has no other support than that of its two extremities. One would suppose that their own weight would sink them; but it is certain that the masses remain floating during the inundation, which lasts some days[109].
You must now be fully satiated with this account of the constant fatigue and labour to which our little pismires are doomed by the law of their nature; I shall therefore endeavour to relieve your mind by introducing you to a more quiet scene, and exhibit them to you during their intervals of repose and relaxation.
Gould tells us that the hill-ant is very fond of basking in the sun, and that on a fine serene morning you may see them conglomerated like bees on the surface of their nest, from whence, on the least disturbance, they will disappear in an instant[110]. M. Huber also observes, after their labours are finished, that they stretch themselves in the sun, where they lie heaped one upon another, and seem to enjoy a short interval of repose: and in the interior of an artificial nest, in which he had confined some of this species, where he saw many employed in various ways, he noticed some reposing which appeared to be asleep[111].