Insect life: Souvenirs of a naturalist

by Jean-Henri Fabre

The result greatly surpassed my expectations. The earthen stopper made by me was pierced with a round hole, noways differing from that made by the mason bee through its mortar dome. The vegetable barrier, so new to my prisoner,—namely, the Sorghum cylinder,—was likewise opened by a hole, apparently made by a single effort, and the gray paper allowed the insect to pass, not by bursting through, but once more by a neat round hole. So my bees were capable of work for which they were not created. To issue from their reed cells they did what probably none of their race ever did before; they perforated the Sorghum pith and made a hole in the paper just as they would have done with their natural clay ceiling. When the moment came to free themselves, the nature of the obstacle was no hindrance so long as it was not too strong for them, and thenceforward the plea of incapacity could not be evoked where a mere paper barrier was in question.

At the same time as the reed cells, two intact nests on their pebbles were placed under the glass bell. On one I pressed closely a sheet of gray paper over the mortar dome, so that to come forth the insect must first pierce the dome and then the paper, no space being left between them; while a little cone of gray paper was gummed on the stone [[293]]round the other nest, so that, as in the first case, there was a double barrier, an earthen and a paper one, with, however, this difference—that the two barriers were not close together, there being a space between them of about a centimetre at the base, and increasing as the cone rises. The results of these two experiments were quite unlike. The Hymenoptera from the nest where paper had been applied to the dome came forth by piercing the double barrier, the outer one being pierced by a clean round hole, as in the reed cells closed in the same way. For the second time it is shown that if the bee is stopped by a paper barrier, the cause is not incapacity to deal with such an obstacle. On the other hand, after they had pierced their earthen vault, the dwellers in the second nest who found the sheet of paper a little way off, made no attempt to overcome the obstacle over which they would so easily have triumphed had it been attached to the nest. They died under the cover without an effort for freedom. So had perished Réaumur’s bees under his glass tube when there was but a bit of gauze between them and freedom. This fact appears to me rich in consequences. What! Here are strong insects which find penetrating tufa mere play, and a stopper of thin wood or a sheet of paper quite easy to pierce, new as these are to them, and yet these vigorous insects let themselves stupidly perish imprisoned in a cone of paper which they might have torn to bits with one bite of their mandibles. They might—but they never dreamed of doing so. The motive of their dull inertness can be only this—the insect is excellently endowed with tools and instinctive [[294]]faculties, in order to accomplish the final act of its metamorphosis, i.e. issuing from the cocoon or cell. Its mandibles furnish it with scissors, file, pick, and lever to cut, gnaw, and pull down not only its cocoon and wall of mortar, but any other barrier not too tenacious which may be substituted for the natural wall of its nest. Moreover,—and this is a chief condition, without which its outfit would be useless,—there is, I will not say the will to use these tools, but an inward stimulus inviting it to employ them. The hour to come forth having arrived, this stimulus awakens, and the insect sets to work to bore a passage.

In that case it matters little whether the material to be pierced is natural mortar, Sorghum pith, or paper. The imprisoning cover will not resist long. It even matters little if the obstacle be thickened and a paper barrier be added to the earthen one. Both count as one if there be no interval between them, and the insect passes through them because this coming forth seems to it a single action. With the paper cone, whose wall is at a short distance, the conditions are changed, although the total thickness of barrier is really the same. The insect has done all that it was destined to do in order to free itself. To move freely on the mortar dome means to it that deliverance is achieved. It has bored its way out; the work is accomplished. But round the nest another barrier presents itself—the paper wall. To pierce through, the action already accomplished must be repeated—that action which the insect has to perform but once in its life. It must double that which naturally is but single; and it [[295]]cannot, simply because it has not the will to do it. It perishes for lack of the smallest ray of intelligence. Yet in this singular intellect it is the fashion nowadays to see a rudiment of human reason! The fashion will pass and the facts remain, bringing us back to the good old ideas of the soul and its immortal destinies.

Réaumur relates, too, how his friend Du Hamel, having seized a mason bee with his pincers when it had entered half-way into its cell, head first, to fill it with bee-bread, carried it into a room at a considerable distance from the spot where he caught it. The bee escaped and flew through the window. Du Hamel immediately returned to the nest. The mason bee reached it almost at the same time, and resumed work. It only seemed a little wilder, says the narrator.

Why were you not with me, venerated master, on the banks of the Aygues, with their stretches of pebbles, dry for three parts of the year, and an enormous torrent when it rains? I would have shown you something far better than the fugitive escaped from your pincers. You should have seen, and shared my surprise thereat, not the short flight of a mason bee, which, carried into a room near at hand, escapes and returns straight home in a neighbourhood familiar to her, but long journeys by unknown ways. You would have seen the bee, carried away by me to a long distance, return with a geographical precision which the swallow would not disown, or the martin, or the carrier-pigeon, and you would have asked yourself, as I did, what inexplicable knowledge of the map of the country guides this mother [[296]]in seeking her nest. Let us come to the facts. We must repeat on the mason bee my earlier experiments with the Cerceris—namely, carrying the insect in darkness far from the nest, marking and setting it free. In case any one should wish to repeat the experiment, I will explain my method of operation, which may make it easier for a beginner. The insect destined for a long journey must of course be captured with certain precautions. No nippers, no pincers which might maim a wing, strain it, and endanger power of flight. While the bee is absorbed in work within her cell, I cover the latter with a little glass tube. As she flies out she goes into this, and thus, without touching her, I can transfer her to a twist of paper and close it quickly. A botanical tin serves as a means of transporting the captives, each in its paper prison.

It is on the spots chosen as starting-places that the most delicate operation takes place—namely, marking each captive before freeing her. I use chalk powdered fine and moistened with a strong solution of gum arabic. Dropped somewhere on the insect with a straw, it leaves a white mark, which dries quickly and adheres to the bee’s fleece. If a mason bee has to be marked, so as to distinguish her from another in an experiment of short duration, such as I shall presently describe, I only touch the tip of the abdomen with a straw charged with colour while the insect is half inside the cell, head down-wards. The bee does not notice the slight touch and works on undisturbed; but the mark is not very durable, nor at a spot favourable for its preservation, since the bee frequently brushes her body to [[297]]detach pollen, and sooner or later effaces it. It is therefore in the very middle of the thorax—between the wings—that I drop the gummed chalk.

In such work it is hardly possible to wear gloves. The fingers require all their dexterity to seize the mason bee with sufficient delicacy, and to master her struggles without rough pressure. It is evident that if nothing else be gained, one is sure of stings; with a little address they can generally be avoided, but not always; one must take them with resignation. Besides, a mason bee’s sting is by no means so painful as that of a hive bee. The white spot dropped on the thorax—off goes the mason bee, and the mark dries as she goes.

The first time I tried the experiment I took two mason bees busy at their nests on the boulders covering the alluvial lands along the Aygues, not far from Serignan, and carried them to my home at Orange, where I freed them after marking each. According to the Ordnance map the distance between the two places is about four kilometres in a right line. The captives were freed in the evening at an hour when bees begin to leave off work, so it was likely that my two would spend the night somewhere near.

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 [[298]]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.