Part 21

The next morning I returned to the nests. It was still too cold, and work was suspended. When the dew was dried the masons set to work. I saw a bee, but without the white spot, taking pollen to one of the two nests whence had come the travellers whom I expected. A stranger, having found the cell unoccupied, and having expatriated the owner, had established herself there, unaware that it was the property of another. Perhaps she had been storing it since the previous evening. Towards ten o’clock, at the hottest time, suddenly the proprietor arrived. Her rights as first occupier were inscribed as far as I was concerned in irrefutable characters in white chalk on her thorax. Here was one of my travellers come back.

Over waves of corn, over fields of red sainfoin, she had accomplished the four kilometres, and returned to her nest after collecting booty on the way, for she came,—worthy creature that she was!—all yellow underneath with pollen. To return from the verge of the horizon was a marvel, but to do so with a well-furnished pollen brush was really sublime economy! A journey, even if compulsory, is always for a bee an opportunity of collecting food. She found the stranger in her nest. “What’s all this? You just wait!” and fell furiously on the other, who perhaps had thought no wrong. Then there were hot pursuits through the air. From time to time the two hovered almost motionless, facing one another with a couple of inches between them, doubtless measuring each other with their eyes, and humming abuse at one another. Sometimes one, sometimes the other alighted on the nest in question. I expected to see a wrestle, and stings used; but I was mistaken. The duties of maternity spoke too imperiously to allow them to risk life, and wipe out the injury in a mortal duel. All was limited to hostile demonstrations and a few tussles leading to nothing.

However, the proprietor seemed to draw redoubled courage and strength from consciousness of her rights. She encamped permanently on the nest and received the other bee each time that she ventured to approach with an irritated quiver of the wings in token of just indignation. The stranger finally withdrew discouraged, and instantly the mason resumed work as actively as if she had not undergone the chances and changes of a long journey.

Yet another word as to rights of property. While a mason bee is absent it is not unusual for some homeless vagabond to visit the nest, take a liking to it, and set to work, sometimes at the same cell, sometimes at the next, if there are several free, as often happens with old nests. When the first occupant returns she does not fail to drive away the intruder, who always ends by getting the worst of it, so lively and invincible is the real owner’s sense of property. Reversing the savage Prussian maxim, “Strength before right,” here right comes before strength; otherwise the constant retreat of the intruder would be quite inexplicable, since the latter’s strength is in no way inferior to that of the real owner. If she has less audacity it must come from not feeling braced by the sovereign strength of being right, which decides among equals, even in the brute creation.

The second of my two travellers did not appear, either on the day when the first came, nor later. I decided to make another experiment—this time with five subjects. Place of starting and arrival, distance and hours, were the same. I found three at the nests on the following day; two were missing.

It is therefore quite clear that Chalicodoma muraria carried away four kilometres, and, set free where she certainly could never have been before, can return home. But why did one out of two, and two out of five, fail to do so? What one could do, why not another? Are they not equally gifted with the faculty which guides them through the unknown? Is it not rather inequality in the power of flight? I recollected that my Hymenoptera did not all fly off with the same energy; hardly were some out of my fingers, launching themselves impetuously into the air, than I lost sight of them, while others let themselves drop a few paces off after a short flight. It seems certain that these had suffered during the journey—perhaps from the concentrated heat in the furnace of my box, or I may have harmed the jointure of the wings while marking them—an operation difficult to perform when one has to avoid being stung. These are maimed, weak creatures—unable to go on with all sail spread, as they ought, for this journey. The experiment must be tried again, only counting those bees which instantly leave my fingers with a swift, strong flight. We shall omit those which hesitate or linger close by on some bush. Moreover, I will do my best to compute the time employed in returning to the nest.

Such an experiment requires a considerable number of subjects, as the weak and maimed, who may be many, must be rejected. Chalicodoma muraria cannot furnish the quantity needed; it is not common enough, and I am anxious not to disturb the small people by the Aigues whom I want for other observations later. Fortunately I have near my house, under the projecting edge of the roof of a shed, a magnificent colony of Chalicodoma sicula in full activity. I can draw at pleasure on the populous city. The insect is small—less than half the size of C. muraria; no matter—all the more merit if it can traverse the four kilometres which I have in reserve for it, and find its nest. I took forty, isolating them as usual in paper cones.

A ladder was placed against the wall in order to reach the nest; it was to be used by my daughter Aglaë, to allow her to mark the exact instant when the first one returned. I set the clock on the mantelpiece and my watch together, that I might compare the moment of departure and arrival. Then I carried off my forty captives to the spot where Chalicodoma muraria works beside the Aygues. The expedition had a double scope—to observe Réaumur’s mason bee and set the Sicilian one free. The latter would have to fly back four kilometres.

At length my prisoners were released—all marked with a large white dot in the middle of the thorax. It is not for nothing that one successively handles forty wrathful Hymenoptera which forthwith unsheath and make play with their poisoned stings. Before the mark could be made, too often the stab was given, and my burning fingers moved in self-defence sometimes against my will; I handled them with more consideration for myself than for the insect, and sometimes squeezed my bees too hard. To experiment in order to lift a small corner of the veil that covers a truth is a beautiful and noble thing, which can enable one to brave many perils, yet surely one may show a little impatience if in a brief space of time one’s finger tips get stung forty times. If any one should reproach me for my clumsy handling, I would suggest that he make the experiment, and then judge how far the situation was pleasant.

In short, either from the fatigue of the journey, or because I pressed too hard and injured some articulations, out of my forty Hymenoptera only twenty flew off strongly and unhesitatingly; the rest strayed over the herbage near at hand, unable to keep their balance, or remained on the willows where I had put them, refusing to fly even when excited by a straw. These faint-hearted ones, these maimed ones, these incapables hurt by my fingers, must be struck off the list. Twenty started with an unhesitating flight. That was amply sufficient.

At the moment of departure there was nothing special in the direction taken—nothing of that straight line to the nest which the Cerceris took in a like case. As soon as they were free the Chalicodoma fled scared—one in this direction, one to a completely opposite point; but, as far as their fiery flight allowed, I think I saw a rapid return of those bees which had flown in the wrong direction for their nests, and most seemed to go to that side of the horizon. I leave this point with the doubts unavoidable with regard to insects lost sight of at some twenty metres distance. So far the experiment had been favoured by calm weather, but now things grew complicated. The heat was stifling, and the sky grew stormy. Rather a strong wind rose, blowing from the south—the very direction which my bees should take to return home. Could they overcome this contrary current and cleave this aerial torrent with their wings? If they try it they must keep close to the ground, as I saw those Hymenoptera doing which continued to work, but it appeared out of the question to soar into the high regions where they might obtain a clear acquaintance with the surrounding country. It was therefore with great apprehension as to the success of my experiment that I returned to Orange after again trying to learn some secret from the bees on the Aygues pebbles.

Hardly had I entered my house when I saw Aglaë, flushed with excitement. “Two,” she cried—“two came at twenty minutes to three, all laden with pollen!” A friend chanced to have come in—a grave legal personage, who, hearing what was on hand, forgot the Code and stamped paper, and insisted on also watching for the arrival of my homing pigeons. The result interested him more than did the lawsuit about the partition wall. In a Senegalian sun and furnace heat reflected from the wall, every five minutes did he mount the ladder bareheaded, with no other protection against sunstroke than his thick, gray locks. Instead of the single watcher whom I had posted I found two good pairs of eyes watching the bees’ return. I had freed them about two o’clock, and the first two returned to the nest at twenty minutes to three, so that three-quarters of an hour had sufficed for travelling four kilometres,—a very striking result, especially if we remember that the bees worked on the road, as was proved by the pollen on their bodies, and besides they must have been hindered by having the wind against them. Two more came back under my eyes, and they had signs of having worked on the way by their load of pollen. As it was growing late, observations could not be continued. When the sun goes down the mason bees leave the nest and take refuge I know not where—here and there—perhaps under roof tiles and in little shelters in walls. I could not count on the arrival of the others until work was resumed in full sunshine.

The next day, when sunshine recalled the scattered workers, I again counted the bees with white dots on their thorax. My success surpassed all my hopes; I counted fifteen—fifteen of the deported bees storing or building as if nothing had happened! Then the storm, which had threatened more and more, burst, and a succession of rainy days stopped all further observations.

Such as it was, the experiment sufficed. Out of twenty bees which seemed fit for the journey when released, fifteen at least had come back—two in the first hour, and three in the course of the evening, and the rest next morning. They had come back in spite of having the wind against them, and—a yet greater difficulty—in spite of their unfamiliarity with the place whither I had transported them. There could be no question that it was for the first time that they saw the osier beds of the Aygues which I had chosen as the starting-place. Never on their own account had they gone so far afield, for they find all they want by way of building material and food close to my shed. The road at the foot of the wall furnishes mortar; the meadows round my house offer nectar and pollen. Economical of time as they are, they would not fly four kilometres to procure what abounds close to the nests. I see them daily taking material from the road, and making a harvest on the meadow flowers, especially on Salvia. According to all appearance they do not fly beyond a circle of a hundred metres. How then did my exiles return? What guided them? Not memory, certainly, but some special faculty, which we can only recognise by its astonishing effects without pretending to explain it, so far outside our own psychology is it.

XXII

AN EXCHANGE OF NESTS

Let us continue our series of experiments on Chalicodoma muraria. From its position on a stone which one can move at will, its nest lends itself to very interesting trials. This is the first of them. I change the place of a nest by carrying the pebble it is placed on some couple of yards away. Edifice and base forming but one, the move was made without at all disturbing the cells. I set the pebble in an open place well in sight, as it was before. When the bee returned, she could not fail to see it.

After a few minutes the owner arrived and went straight where the nest used to be. She hovered gently just above the vacant spot, looked, and alighted just where the stone used to lie. There she walked about, searching pertinaciously, then soared up and flew away. Her absence was short; she came back speedily and resumed her search on foot or on the wing—always on the spot formerly occupied by the nest. A new fit of irritation expressed by a sudden flight through the osier bed, then as sudden a return and resumption of the vain search—always over the impression left by the pebble which I had carried away. These sudden flights, prompt returns, and obstinate examinations of the empty place, were repeated very many times before the mason bee could believe her nest was gone. She certainly must have seen it in its new position, for sometimes she flew only a few inches above it, but she did not care about it. For her it only represented the nest of another bee.

Often the experiment ends without so much as a visit to the stone carried three or four yards away; the bee departs and does not return. If the distance be less—say a yard—sooner or later she alights on the pebble on which her nest is built. She will visit the cell which she was making or storing a little while earlier, plunge in her head several times, examine the surface of the stone narrowly, and after much hesitation return to search over the original spot. The nest, which is no longer in its right place, is altogether abandoned, though it be but a yard away. Vainly does the bee alight on it; she cannot recognise it as hers. I convinced myself of this by finding it several days later in just the same state as when I moved it. The cell, half filled with honey, was still open, allowing the ants to pillage it; the cell in process of construction was unfinished, without a single new course of mortar. Of course the bee may have returned, but she had not resumed her work. The displaced abode was abandoned for ever.

I shall not deduce the strange paradox that a bee, capable of returning home from a great distance, is yet incapable of finding it a yard off; the interpretation of the facts does not involve this. The conclusion appears to be that she retains a tenacious impression of the spot occupied by the nest, returning there with an indefatigable obstinacy when the nest is gone. But of the nest itself she has a very vague notion—does not recognise her own masonry kneaded with her own saliva, nor the honey paste she had collected. Vainly does she visit her work, the cell; she abandons it, not acknowledging it any more, since the place where lies the pebble is no longer the same.

We must own that insect memory is a strange one, so lucid in general knowledge of locality, so limited as to its home. I should be disposed to name it topographical instinct; the creature knows the localities, but not the dear nest—the dwelling. The Bembex led us to a like conclusion. The nest being laid open, she cared nothing for the family—for the larva writhing distressfully in the sun unrecognised. What they do recognise, what they seek, and find with marvellous precision, is the place where no longer exists anything of the entrance door—not even a threshold.

If any doubt remain as to the powerlessness of Chalicodoma muraria to know her nest except by the place which the pebble occupies on the ground, this may set it at rest. I substituted a nest of one mason bee for that of another, as alike as might be, both in masonry and storage. Of course this exchange and those of which I shall speak later were made during the absence of the owner. In the nest not hers, but placed where her own had been, she established herself without hesitation. If she had been building, I offered her a cell in process of construction, and she worked on with the same care and zeal as if the work already done had been her own. If she were bringing honey and pollen, I offered a cell partly stored. Her journeys continued, with honey in her crop and pollen underneath her body to complete filling the store of another bee.

Thus the bee does not suspect the exchange, nor distinguish what is and is not hers. She thinks she is continuing to work at a cell really her own.

After leaving her for a time in possession of the exchanged nest, I restored her own. The fresh change passed unobserved; her labour was continued in the cell restored to her, at the point at which it had arrived in the substituted one. Then I once more substituted the strange nest, and still she persisted in her labour. Thus alternating nests at the same spot, I thoroughly convinced myself that the insect cannot perceive the difference between that which is her own and that which is not. Whether the cell be hers or not, she works with equal fervour, provided that the basis for the edifice—the stone—remains in its original position.

One may lend a livelier interest to the experiment by using two neighbouring nests—work at which is about equally advanced. I transpose them, placing one where the other was; the distance is hardly a cubit. Despite this close neighbourhood, which allows the bees to see both nests at once and choose between them, the two bees on arriving each immediately alighted on the substituted nest and went on working at it. We may change the two nests at pleasure; we shall still see the two mason bees keep to the spot chosen by them and work in turn—now at their own cell, now at that of the other.

It may be thought that the confusion was caused by a close resemblance between the two nests, since, at first little expecting the results obtained, I began by choosing those as much alike as possible, lest the bees should be repelled. My caution presupposed a clear-sightedness the insect did not possess. I now took two nests exceedingly unlike, except that in each the bee found a cell advanced in its work to the same point. The first was an old nest, with the dome pierced with eight holes, the orifices of cells of a preceding generation; one of these had been restored, and the bee was storing it. The second was a new nest, with no dome, and composed of a single cell with little stones on the outside. Here too the bee was storing her paste. Certainly no two nests could differ more: the one with its eight vacant rooms, and its ample dome of clay, the other with a single cell—bare, and at most the size of an acorn.

Well, the two mason bees did not hesitate long before the two exchanged nests—hardly a yard apart. Each went to the site of its former abode. The owner of the old nest found but a single cell. She rapidly inspected the stone, and without further ceremony first plunged her head into the cell to disgorge honey, and then her hind-quarters to drop pollen. And this was no action performed to rid herself as soon as possible of a trying burden, for she flew away and quickly returned with fresh stores to be laid up. This bringing provisions to another’s larder was repeated as often as I would allow. The other bee, finding, instead of one cell a spacious building with eight chambers, was at first considerably embarrassed. Which of the eight was the right one?—in which was her heap of bee bread? She plunged down into each room, and at length found what she was seeking—a condition like that which she had left when she took her last journey, the beginning of a store of food. From that moment she behaved like her neighbour, and carried honey and pollen to a cell not made by her.

Let us restore the nests to their natural places, exchanging them afresh. Each bee, after a little hesitation, sufficiently explained by the very great difference between the two nests, will work alternately in her own cell and the strange one. At length the egg is laid and the cell closed, whichever the nest may be that she is occupied with at the moment when the provisions are sufficient. Such facts show clearly why I hesitate to give the name of memory to the singular faculty that brings back the insect so accurately to the site of her nest, yet does not allow her to distinguish her work from that of another, however great may be the difference of appearance between them.

Now let us experiment on Chalicodoma muraria from another psychological point of view. Here is a mason bee at work on the first course of her cell; in exchange I give her one not only completed, but half full of honey, which I stole from an owner who would speedily have laid an egg there. What will the mason do with this munificent gift which spares her the labour of building and storage? Leave her mortar, of course, lay an egg, and close all up. Not at all! the animal finds our logic illogical. The insect obeys an inevitable, unconscious impulse. It has no choice as to what it shall do,—no discernment as to what is and is not desirable,—but glides, as it were, down an irresistible slope prepared for it beforehand to bring it to a determined end. The facts still to be stated affirm this strongly.

The bee, which is building, and to which I offer a cell ready made and full of honey, will not give up building for that; she is following her trade as mason, and once on that tack, led on by unconscious impulse, she must needs build, even if her labour be superfluous and contrary to her interests. The cell I give her is certainly quite complete in the opinion of its own constructor, since the bee from whom I subtracted it was finishing the store of honey. To touch it up, and, above all, to add to it is useless and absurd. All the same the bee which is building will build. On the orifice of the honey store she lays another layer of mortar, then another and another, until the cell is actually a third beyond its usual height. Now the task is done—not as well indeed as if the bee had continued the cell whose foundations she was laying when the nests were exchanged, but certainly in a way more than enough to demonstrate the irresistible impulse which drove the builder on. Then came the storing, likewise abridged, for otherwise the honey would overflow by the union of the stores of two bees. Thus the mason bee, which is beginning to build, and to which one gives a cell completed and filled with honey, alters nothing in the order of her work. First she builds and then she stores; only she shortens her labours—instinct warning her that the height of the cell and quantity of honey are beginning to assume proportions too great.