Chapter 16

_THE SAME SUBJECT CONTINUED._

I have collected my chief observations on swarms in the two preceding letters; those most frequently repeated, and of which the uniformity of result leads me to apprehend no error. I have deduced what seem the most direct consequences; and in all the theoretical part, I have sedulously avoided going beyond facts. What is yet to be mentioned is more hypothetical, but it engrosses several curious experiments.

It has been demonstrated, that the principal motive of the young females departing when hives swarm, is their insuperable antipathy to each other. I have repeatedly observed that they cannot gratify their aversion, because the workers with the utmost care prevent them from attacking the royal cells. This perpetual opposition at length creates a visible inquietude, and excites a degree of agitation that induces them to depart. All the young queens are successively treated alike in hives that are to swarm. But the conduct of the bees towards the old queen, destined to conduct the first swarm, is very different. Always accustomed to respect fertile queens, they do not forget what they owe to her; they allow her the most uncontrouled liberty. She is permitted to approach the royal cells; and if she even attempts to destroy them, no opposition is presented by the bees. Thus her inclinations are not obstructed, and we cannot ascribe her flight, as that of the young queens, to the opposition she suffers. Therefore, I candidly confess myself ignorant of the motives of her departure.

Yet, on more mature reflection, it does not appear to me that this fact affords so strong an objection against the general rule as I had at first conceived. It is certain at least, that the old queens, as well as the young ones, have the greatest aversion to the individuals of their own sex. This has been proved by the numerous royal cells destroyed. You will remember, Sir, that in my first observations on the departure of old queens, seven royal cells opened at one side were destroyed by the queen. If rain continues several days, the whole are destroyed; in this case, there is no swarm, which too often happens in our climate, where spring is generally rainy. Queens never attack cells containing an egg or a very young worm; but only when the worm is ready for transforming to a nymph, or when it has undergone its last metamorphosis.

The presence of royal cells with nymphs or worms near their change, also inspires old queens with the utmost horror or aversion; but here it would be necessary to explain why the queen does not always destroy them though it is in her power. On this point, I am limited to conjectures. Perhaps the great number of royal cells in a hive at once, and the labour of opening the whole, creates insuperable alarm in the old queen. She commences indeed with attacking her rivals; but, incapable of immediate success, her inquietude during this work becomes a terrible agitation. If the weather continues favourable, while she remains in this condition, she is naturally disposed to depart.

It may easily be understood, that the workers accustomed to respect their queen, whose presence is a real necessity to them, crowd after her; and the formation of the first swarm creates no difficulty in this respect. But you will undoubtedly ask, Sir, What motive can induce the workers to follow their queen from the hive, while they treat the young queens very ill, and, even in their most amicable moments, testify perfect indifference towards them. Probably it is to escape the heat to which the hive is then exposed. The extreme agitation of the females leads them to traverse the combs in all directions. They pass through groupes of bees, injure and derange them; they communicate a kind of delirium, and these tumultuous motions raise the temperature to an insupportable degree. We have frequently proved it by the thermometer. In a populous hive it commonly stands between 92 deg. and 97 deg., in a fine day of spring; but during the tumult which precedes swarming, it rises above 104 deg. And this is heat intolerable to bees. When exposed to it, they rush impetuously towards the outlets of the hive and depart. In general they cannot endure the sudden augmentation of heat, and in that case quit their dwelling; neither do those returning from the fields enter when the temperature is extraordinary.

I am certain, from direct experiments, that the impetuous courses of the queen over the combs, actually throws the workers into agitation; and I was able to ascertain it in the following manner. I wished to avoid a complication of causes. It was particularly important to learn, whether the queen would impart her agitation but not at the time of swarming. Therefore I took two females still virgins, but capable of fecundation for above five days, and put one in a glass hive sufficiently populous; the other I put into a different hive of the same kind. Then I shut the hives in such a way that there was no possibility of their escape. The air had free circulation. I then prepared to observe the hives every moment that the fineness of the weather would invite both males and females to go abroad, for the purpose of fecundation. Next morning, the weather being gloomy, no male left the hive, and the bees were tranquil; but towards eleven of the following day, the sun shining bright, both queens began to run about seeking an exit from every part of their dwelling; and from their inability to find one, traversed the combs with the most evident symptoms of disquiet and agitation. The bees soon participated of the same disorder; they crowded towards that part of the hive where the openings were placed; unable to escape they ascended with equal rapidity, and ran heedlessly over the cells until four in the afternoon. It is nearly about this time that the sun declining in the horizon recalls the males; queens requiring fecundation never remain later abroad. The two females became calmer, and tranquillity was in a short time restored. This was repeated several subsequent days with perfect similarity; and I am now convinced that there is nothing singular in the agitation of bees while swarming, but that they are always in a tumultuous state when the queen herself is in agitation.

I have but one fact more to mention. It has already been observed, that on losing the female, bees give the larvae of simple workers the royal treatment, and, according to M. Schirach, in five or six days they repair the loss of their queen. In this case there are no swarms. All the females leave their cells almost at the same moment, and after a bloody combat the throne remains with the most fortunate.

I can very well comprehend that the object of nature is to replace the lost queen; but as bees are at liberty to choose either the eggs or worms of workers, during the first three days of existence; to supply her place, why do they give the royal treatment to worms, all of nearly an equal age, and which must undergo their last metamorphosis almost at the same time? Since they are enabled to retain the young females in their cells, why do they allow all the queens, reared according to Schirach's method, to escape at once. By prolonging their captivity more or less, they would fulfil two most important objects at once, in repairing the loss of their females and preserving a succession of queens to conduct several swarms.

At first it was my opinion, that this difference of conduct proceeded from the difference of circumstances in which they found themselves situated. They are induced to make all their dispositions relative to swarming only when in great numbers, and when they have a queen occupied with her principal laying of male eggs; whereas, having lost their female, the eggs of drones are no longer in the combs to influence their instinct. They are in a certain degree restless and discouraged.

Therefore, after removing the queen from a hive, I thought of rendering all the other circumstances as similar as possible to the situation of bees preparing to swarm. By introducing a great many workers, I encreased the population to excess, and supplied them with combs of male brood in every stage. Their first occupation was to construct royal cells after Schirach's method, and to rear common worms with royal food. They also began some stalactite cells, as if the presence of the male brood had inspired them to it; but this they discontinued, as there was no queen to deposit her eggs. Finally, I gave them several close royal cells, taken indifferently from hives preparing to swarm. However, all these precautions were fruitless; the bees were occupied only with replacing their lost queen; they neglected the royal cells entrusted to their care; the included queens came out at the ordinary time, without being detained prisoners a moment; they engaged in several combats, and there were no swarms.

Recurring to subtleties, we may perhaps suggest a cause for this apparent contradiction. But the more we admire the wise dispositions of the author of nature, in the laws he has prescribed to the industry of animals, the greater reserve is necessary in admitting any theory adverse to this beautiful system, and the more must we distrust that facility of imagination from which we think by embellishment to elucidate facts.

In general, Naturalists who have long observed animals, and those in particular who have chose insects for their favourite study, have too readily ascribed to them our sentiments, our passions, and even our intentions and designs. Incited to admiration, and disgusted perhaps by the contempt with which insects are treated, they have conceived themselves obliged to justify the consumption of time bestowed on this pursuit, and they have painted different traits of the industry of these minute animals, with the colours inspired by an exalted imagination. Nor is even the celebrated Reaumur to be acquitted of such a charge. He frequently ascribes combined intentions to bees; love, anticipation, and other faculties of too elevated a kind. I think I can perceive that although he formed very just ideas of their operations, he would be well pleased that his reader should admit they were sensible of their own interests. He is a painter who by a happy interest flatters the original, whose features he depicts. On the other hand, Buffon unjustly considers bees as mere automatons. It was reserved for you, Sir, to establish the theory of animal industry on the most philosophical principles, and to demonstrate that those actions that have a moral appearance depend on an association of ideas _simply sensible_. It is not my object here to penetrate those depths, or to insist on the details.

But, on the whole, facts relative to the formation of swarms perhaps present more subjects of admiration than any other part of the history of bees. I think it proper to state, in a few words, the simplicity of the methods by which the wisdom of nature guides their instinct. It cannot allow them the slightest portion of understanding; it leaves them no precautions to be taken, no combination to be followed, no foresight to exercise, no knowledge to acquire. But having adapted their sensorium to the different operations with which they are charged, it is the impulse of pleasure which leads them on. She has therefore pre-ordained all that is relative to the succession of their different labours; and to each operation she has united an agreeable sensation. Thus, when bees construct cells, watch over their larvae, and collect provisions, we must not seek for method, affection, or foresight. The only inducement must be sought for in some pleasing sensation attached to each of these operations. I address a philosopher; and as these are his own opinions applied to new facts, I believe my language will be easily understood. But I request my readers to peruse and to reflect on that part of your works which treats of the industry of animals. Let me add but another sentence. The inducement of pleasure is not the sole agent; there is another principle, the prodigious influence of which, at least with regard to bees, has hitherto been unknown, that is the sentiment of aversion which all females continually feel against each other, a sentiment whose existence is so fully demonstrated by my experiments, and which explains many important facts in the theory of swarms.

_PREGNY, 10. September 1791._