CHAP. X. ESTABLISHMENT OF A MIXED ANT-HILL IN A GLASS APPARATUS.

I had often established, with success, artificial ant-hills, and am indebted to them for several interesting observations on the Fallow, Yellow, and other ants. I now resolved upon making the attempt of fixing, in an apparatus of the same kind, a colony of Amazon Ants, with their auxiliaries. The knowledge I had already acquired upon mixed ant-hills greatly facilitated my views. In describing the particulars of this experiment, the manners of these two species will be completely developed.

I constructed an apparatus, to which, for the sake of abridgement, I shall, as formerly, give the name of ruche. It consisted of a double vertical frame, twenty inches in length, by ten in depth, glazed on both sides; the distance between the two frames was only ten lines. I found this, however, too great, and, therefore, lessened it by placing a sheet of tin, drilled in numerous places, parallel with the two glasses. On the fore-part of the ruche was a vertical portcullis, which could be raised or lowered at will, thus answering as a door. (This apparatus should not be raised upon feet, like those I have before described, but should be so constructed as to rest immediately upon the earth, by means of two very strong liteaux, inserted in the bottom of the ruche, and projecting, on each side.) Two wooden shutters excluded the light, and several holes, drilled in the upper part of the apparatus, allowed of my presenting honey to the ants, or pouring water into the interior, as often as it should be judged necessary. It was in this ruche, of which we may see a figure in Plate 1. that I thought of establishing a mixed ant-hill; and was desirous the ants should settle there of their own accord. To render them less sensible of the singularity of their abode, I filled the lower half of this apparatus with fine and slightly moistened earth, and deposited honey in several places.

These preparations being finished, I chose one of the most populous mixed ant-hills, in which were many males and young Amazon females. I removed a great part of this nest, placed it in a large linen bag, and then carried it to my study.

I established between my prisoners, and the lodging they were to occupy a free communication by means of a little canal of wood glazed on its upper surface, having one of its extremities inserted into the bag, and the other into the door of the ruche. This done, I left the ants to themselves. On the following morning I saw some of the Ash-coloured Ants leave the bag and enter the ruche through the glazed canal. In the evening more passed. The second day they commenced carrying each other into the apparatus. Their number augmented hourly. At length the canal scarcely sufficed for the crowd of insects going and returning; it was obstructed by the recruits, and these were, for the most part, engaged in transporting the Legionary Ants from the bag to the ruche.

Having this glazed conduit, I was not obliged to open the shutters to see what was passing. The advantage of this arrangement was, that of not alarming the ants, whilst it assured me of their forming an establishment in the artificial ant-hill, preparing lodgings there, and removing the useless materials, such as flints or pebbles, and pieces of earth too dry to be put in work. I found from this, that it was necessary to moisten the earth in the interior, and, therefore, poured water through the holes in the upper part of the apparatus, which completely answered (as will be presently seen) all my wishes.

By the fourth day, the whole of the ants appeared to know the road, and had ceased to carry each other. But as I observed many re-enter the bag, I was fearful they might take the whim of fixing themselves there: I, therefore, obliged them to return into the ruche. With this view, I separated the bag from the glazed canal, and scattered gently all the earth it contained upon the floor near the artificial ant-hill. I constructed all around a brick wall, and reduced between my fingers the several clods; so that the ants could not conceal themselves. I then re-fixed one end of the glazed canal to the door of the ruche, placing the other end on the ground; forming an inclined plane, in such a way that the ants could go out and find their companions roving in the enclosure. The Ash-coloured Ants actually descended by this passage, and immediately brought back into their new abode the stragglers. They looked for them in every corner, visited the smallest clod of earth, examined scrutinously the remains of their former nest, and thence drew their companions of both species, taking them up in their mouths and transporting them immediately to the ruche. This operation finished, I went out to find the rest of the nest which I had left in the field, and then dispersed it in my study; a few of the Ash-coloured, or Negro Ants, in the ruche, perceiving fresh arrivals wandering about the floor, came out, and carried them into the new habitation. I was much astonished on seeing several ants leave the apparatus at the same time, as if they had been told there were many ants still to bring in. They immediately put themselves to work, constantly arriving with their companions of both species suspended by their mandibles, or setting off in file to seek those who still remained unsheltered: whilst these were thus engaged, their companions constructed galleries in the heap of earth I had brought in, and disengaged a great number of labourers, larvæ, and pupæ, which were there imprisoned. They worked with indefatigable activity. I was struck by their zeal. They brought to my recollection those famous dogs, who appear associated in charity with their masters, for the purpose of extricating from underneath the snow of the Alps engulphed travellers.

The Legionary Ants took no active part in this interesting scene: the Negro Ants were particularly careful of them, often conducting them into the interior of the nest, but sometimes contenting themselves with laying them down at the entrance of the glazed canal, going immediately in search of others. The Rufescent Ant, in this case, remained, for a moment, curled up, without movement; it then unrolled itself, and looked around, on all sides, without knowing where it was, or what direction it should take. I saw it, then, approach the Ash-coloured Ants, and implore their assistance, by the aid of its antennæ, until one that had little to do, seized and carried it into the nest.

In eight days the ruche was completely peopled, and I was in hopes I had acquired a sure means of observing what passed in the interior of these singular republics. I hastened, then, to submit it to the proof. For this purpose, I carried out my ruche, and placed it upon the grass, allowing its inhabitants the full liberty of leaving it. I confess this was not done without some degree of apprehension; for I might thus lose, in one moment, the fruit of all my care; but I was encouraged by the hope that the Ash-coloured Ants attached to their work, would not abandon it so readily.

The first day, the Negro Ants, availing themselves of their liberty, visited the environs of their abode. They returned, just as I could wish. Some individual Amazons, also, went out, but were quickly brought back by their auxiliaries. On the day following, the Ash-coloured Ants guarded their door very assiduously; they heaped up many pieces of stone, &c. to narrow it, and thus oppose the entrance of certain ants attracted thither by the odour of the honey. They went, also, in search of the pucerons.

In the evening, the air being extremely warm, and the sun shining upon the ant-hill, I saw the Amazons prepare for an expedition. The whole army descended by means of the glazed canal. The signal being given, they set forward in an entire body, and fell upon a nest of Ash-coloured Ants, situated a few paces from the ruche. The Amazons returned with the success usually attending these incursions. Each disposed of his load at the door of the artificial ant-hill, into which the Ash-coloured Ants immediately introduced it. The warlike ants returned directly to carry off the rest of the larvæ; and, as it was only a trifling distance to the scene of pillage an uninterrupted chain of Amazons was established; some going to seek the pupæ, whilst others were bearing them away. At length they re-entered their own habitation, but came out in a quarter of an hour, and made their last attack upon the ant-hill, purloining, this time but a very few larvæ, and retiring tranquilly to the ruche.

I was greatly pleased on seeing the Amazons return to the artificial ant-hill, and confide their booty to their auxiliaries. This was a flattering omen for the success of my experiment, and from this period I indulged the hope of seeing the manners and habits of these insects fully developed. That I might not alarm them by the introduction of a strong light before they had fully established themselves in the ruche, the shutters were kept, for some time, completely closed. I was, however, extremely impatient to witness the interior, and it was now time to ascertain the extent of their labours, and observe the immediate consequences attending the capture of the pupæ. When I opened the shutters, I was agreeably surprised in viewing, at one glance, the whole of the interior of the ant-hill. The ants had mined the entire mass of earth. The glass, on one side, and the sheet of tin on the other, served as walls to the several chambers they had excavated. All their passages, their halls, even to the smallest apartments, were distinctly visible. They constituted irregular stories, some larger than others, the former were of greater elevation, the latter more elongated or narrowed. It was evident the ants had mined, and not masoned, or worked up the earth: what they had drawn from the interior, was heaped up upon the last ceiling or roof. The walls were rendered so compact and solid as to run little risk of being thrown down by the weight of the materials they supported.

Here the pupæ and larvæ were collected in the large chambers. There the Amazon army was stationed. In another place, the main body of auxiliaries were assembled. I had scarcely time to make these observations, the ants being much alarmed by the sudden introduction of the light. The Amazons left their garrison, and ran over the glass, but re-assembled, in a short time, in the most elevated part of the building, and formed themselves in groups close to the vault or roof. The Negro Ants, at the same moment, seized the larvæ and pupæ, carried them to the darkest places, passed through the holes in the sheet of tin, and reached the side opposite to that where I was taking my observations, the shutter of which had not been opened. By degrees, I was enabled so to manage the light that it should no longer alarm these insects, or at least so triflingly, that tranquillity might be speedily restored. I could thus follow them in their operations (which was absolutely necessary) at my ease.

The Amazons always grouped on or affixed to the ceiling of their underground chambers⁠[1]⁠, did not quit their position, but to approach the Ash-coloured Ants, whose assistance was a point of vital importance. I saw none of them approach the larvæ or pupæ, or touch the provisions I had placed within reach; nor did meat and honey ever tempt them. I witnessed, in its fullest extent, the great care with which the auxiliaries treated them; the latter were constantly occupied in nourishing and brushing them; carrying them from one quarter of the ant-hill to another; conducting them where the temperature was highest, reassembling them with their companions, &c. I also observed a large body of the auxiliaries surrounding a Rufescent female without wings, for whom they expressed great solicitude; the rest of the males and females were on the outside of the ant-hill, attended by a numerous cortége of Ash-coloured Ants, and by some Amazons; they soon took flight and were never seen to return.

Every day the Legionaries made fresh incursions on the neighbouring ant-hills, and thus considerably increased the number of their pupæ: but when once placed within the ruche they were no longer the objects of their attention. It was now the business of the auxiliaries to attend and convey them to the different chambers, which is regulated by the hour of the day and direction of the sun. Some of the pupæ were still enveloped in their cocoon; others had been extricated from them: the Negro Ants often came, notwithstanding my presence, to liberate them from their imprisonment. The cocoon of the Amazon pupæ, consisted of a browner silk than that of the Ash-coloured pupæ, and was also one third longer; but their number did not equal those of the pupæ of the other cast. The larvæ of both species were placed in different apartments, for they had, without doubt, wants relative to their age; but the Ash-coloured Ants alone took care of and nourished them, &c. I once, however, saw an Amazon engaged in removing the last pellicle from one of the Ash-coloured pupæ; the Amazon took it up with the same delicacy as other ants, and the labourer, the object of its care, evinced no symptom of fear on its being so close to this warrior, who did it no injury, and left it as soon as it was liberated. This affords another instance, that the Amazons are not absolutely unqualified for labour.

The ruche exhibited a greater population every day, and a considerable number of Ash-coloured Ants was developed there: these I recognised by their grey colour. I also saw young Amazon Ants, which were a little paler in colour than the old of the same species; both received every attention from the auxiliaries. Tranquillity and unanimity reigned in this mixed colony. The ants appeared perfectly happy in their abode, yet thought, however, of quitting it. The Ash-coloured species, wearied perhaps by the frequent opening and closing of the shutters, began to emigrate, and formed a little cavity in the turf, a few paces from the ruche. I deranged their operations and suspended their emigrations, by placing the ruche in another situation; but some days after they discovered another dwelling, and recommenced their recruiting, when I took the precaution of closing the door, and bringing the artificial ant-hill back to my study. I there kept it a considerable time, and the confirmation was greater, from day to day, of what I had hitherto acquired. When the weather was favourable, (between the hours of three and five), I took it out and placed it on the grass, and always observed the Legionaries pay a visit to the neighbouring ant-hills. At length, expecting no further information, I resolved upon trying an experiment I had frequently meditated, and as often dismissed, on account of my close attachment to my prisoners: this was to bring into immediate combat two Legionary armies.

With this view I waited till I saw the Amazon Ants, inhabiting another mixed ant-hill, which was situated in the garden, quit it; when I hastened to place my artificial ant-hill full in front of their advancing column. After a trifling combat, which took place at the door of the ruche, those in the interior went out in force, when the enemy’s column appeared desirous to avoid battle, taking at first another direction, then returning and re-entering their nest. Several ants from the ruche put themselves in pursuit: some went even as far as the enemy’s garrison, where they were retained; two or three only escaped, and these I observed returned in great haste. The entire army now left the ruche, and proceeded to the mixed ant-hill; I looked forward to a general battle, but when the column had arrived to within a few paces of the entrance, it fell back, with the exception of a small body, composed of about three hundred Legionary Ants, who continued their route, until they reached the ant-hill. The Amazons assembled on the surface appeared extremely agitated, as if they had foreseen the attack with which they were threatened. The combatants fought body to body; but the strangers threw themselves into a gallery with so much impetuosity, that the others could not restrain them. This courageous incursion did not succeed; they all perished, not however, without making great havoc; for when I saw the Amazons of the natural ant-hill resume their expeditions, I found their army reduced to one half its original number. The ruche had not suffered so great a diminution. I replaced it upon the grass, and allowed the Ash-coloured Ants the liberty of emigrating, which they did, in the manner we have already described.