fact, and I shall here add some reflexions. During the period of
swarming, the conduct or instinct of bees seems to receive a particular
modification. At all other times, when they have lost their queen, they
appropriate workers worms to replace her; they prolong and enlarge the
cells of these worms; they supply them with aliment more abundantly, and
of a more pungent taste; and by this alteration, the worms that would
have changed to common bees are transformed to queens. We have seen
twenty-seven cells of this kind constructed at once; but when finished
the bees no longer endeavour to preserve the young females from the
attacks of their enemies. One may perhaps leave her cell, and attack all
the other royal cells successively, which she will tear open to destroy
her rivals, without the workers taking any part in their defence. Should
several queens be hatched at once, they will pursue each other, and
fight until the throne remain with her that is victorious. Far from
opposing such duels, the other bees rather seem to excite the
combatants.
Things are quite reversed during the period of swarming. The royal cells
then constructed are of a different figure from the former. They
resemble stalactites, and in the beginning are like the cup of an acorn.
The bees assiduously guard the cells when the young queens are ready for
their last metamorphosis. At length the female hatched from the first
egg laid by the old queen leaves her cell; the workers at first treat
her with indifference. But she, immediately yielding to the instinct
which urges her to destroy her rivals, seeks the cells where they are
enclosed; yet no sooner does she approach than the bees bite, pull, and
drive her away, so that she is forced to remove; but the royal cells
being numerous, scarce can she find a place of rest. Incessantly
harassed with the desire of attacking the other queens, and incessantly
repelled, she becomes agitated, and hastily traverses the different
groupes of workers, to which she communicates her agitation. At this
moment numbers of bees rush towards the aperture of the hive, and, with
the young queen at their head, depart to seek another habitation.
After the departure of the colony, the remaining workers set another
queen at liberty, and treat her with equal indifference as the first.
They drive her from the royal cells; being perpetually harrassed, she
becomes agitated; departs, and carries a new swarm along with her. In a
populous hive this scene is repeated three or four times during spring.
As the number of bees is so much reduced, that they are no longer
capable of preserving a strict watch over the royal cells, several
females then leave their confinement at once; they seek each other,
fight, and the queen at last victorious reigns peaceably over the
republic.
The longest intervals we have observed between the departure of each
natural swarm have been from seven to nine days. This is the time that
usually elapses after the first colony is led out by the old queen,
until the next swarm is conducted by the first young queen set at
liberty. The interval between the second and third is still shorter; and
the fourth sometimes departs the day after the third. In hives left to
themselves, fifteen or eighteen days are usually sufficient for the
throwing of the four swarms, if the weather continues favourable, as I
shall explain.
A swarm is never seen except in a fine day, or, to speak more correctly,
at a time of the day when the sun shines, and the air is calm. Sometimes
we have observed all the precursors of swarming, disorder and agitation,
but a cloud passed before the sun, and tranquillity was restored; the
bees thought no more of swarming. An hour afterwards, the sun having
again appeared, the tumult was renewed; it rapidly augmented; and the
swarm departed.
Bees generally seem much alarmed at the prospect of bad weather. While
ranging in the fields the passage of a cloud before the hive induces
them precipitately to return. I am induced to think they are disquieted
by the sudden diminution of light. For if the sky is uniformly obscured,
and there is no alteration in clearness or in the clouds dispelling,
they proceed to the fields for their ordinary collections, and the first
drops of a soft rain does not make them return with much precipitation.
I am persuaded that the necessity of a fine day for swarming is one
reason that has induced nature to admit of bees protracting the
captivity of their young queens in the royal cells. I will not deny that
they sometimes seem to use this right in an arbitrary manner. However
the confinement of the queens is always longer when bad weather lasts
several days together. Here the final object cannot be mistaken. If the
young females were at liberty to leave their cradles during these bad
days, there would be a plurality of queens in the hive, consequently
combats; and victims would fall. Bad weather might continue so long,
that all the queens might at once have undergone their last
metamorphosis, or attained their liberty. One victorious over the whole
would enjoy the throne, and the hive, which should naturally produce
several swarms, could give only one. Thus the multiplication of the
species would have been left to the chance of rain, or fine weather,
instead of which it is rendered independent of either, by the wise
dispositions of nature. By allowing only a single female to escape at
once, the formation of swarms is secured. This explanation appears so
simple, that it is superfluous to insist farther on it.
But I should mention another important circumstance resulting from the
captivity of queens; which is, that they are in a condition to fly, when
the bees have given them liberty, and by this means are capable of
profiting by the first moment of sunshine to depart at the head of a
colony.
You well know, Sir, that all drones and workers are not in a condition
to fly for a day or two after leaving their cells. Then they are of a
whitish colour, weak, and their organs infirm. At least, twenty-four or
thirty hours must elapse before the acquisition of perfect strength, and
the development of all their faculties. It would be the same with the
females was not their confinement protracted after the period of
transformation; but we see them appear, strong, full grown, brown, and
in a better condition for flying than at any other period. I have
elsewhere observed, that constraint is used to retain the queens in
captivity. The bees solder the covering to the sides of the cell by a
cordon of wax. As I have also explained how they are fed, it need not be
repeated here.
It is likewise a very remarkable fact, that queens are set at liberty
earlier or later according to their age. Immediately when the royal
cells were sealed, we marked them all with numbers, and we chose this
period because it indicated the age of the queens exactly. The oldest
was first liberated, then the one immediately younger, and so on with
the rest. None of the younger queens were set at liberty before the
older ones.
I have a thousand times asked myself how the bees could so accurately
distinguish the age of their captives. Undoubtedly I should do better to
answer this question by a simple avowal of my ignorance. At the same
time, I must be permitted to state a conjecture. You will admit, that I
have not, as some authors, abused the right of giving myself up to
hypothesis; may not the humming or sound emitted by the young queens in
their cells, be one of the methods employed by nature to instruct the
bees in the age of their queens? It is certain that the female, whose
cell is first sealed, is also the first to emit this sound. That in the
next emits it sooner than the rest, and so on with those immediately
subsequent. As their captivity may continue six days, it is possible
that the bees in this space of time may forget which has emitted it
first; but it is also possible, that the queens diversify the sounds,
encreasing the loudness as they become older, and that the bees can
distinguish these variations. We have even ourselves been able to
distinguish differences in the sound, either with relation to the
succession of notes, or their intensity; and probably there are
gradations still more imperceptible that escape our organs, but may be
sensible to those of the workers.
What gives weight to this conjecture is, that the queens brought up by
M. Schirach's method, are perfectly mute; neither do the workers form
any guard around their cells, nor do they retain them in captivity a
moment beyond the period of transformation, and, when they have
undergone it, they are allowed to combat until one has become
victorious over all the rest. Why? Because the object is only to replace
the last queen. Now, provided that among the worms reared as queens,
only one succeeds, the fate of the others is uninteresting to the bees,
whereas, during the period of swarming, it is necessary to preserve a
succession of queens, for conducting the different colonies; and to
ensure the safety of the queens, it is necessary to avert the
consequences of the mutual horror by which they are animated against
each other. Behold the evident cause of all the precautions that bees,
instructed by nature, take during the period of swarming; behold an
explanation of the captivity of females; and that the duration of their
captivity might be ascertained by the age of the young queens, it was
requisite for them to have some method of communicating to the workers
when they should be liberated. This method consists in the sound
emitted, and the variation they are able to give it.
In spite of all my researches, I have never been able to discover the
situation of the organ which produces the sound. But I have instituted a
new course of experiments on the subject, which are still unfinished.
Another problem still remains for solution. Why are the queens reared,
according to M. Schirach's method, mute, whilst those bred in the time
of swarming have the faculty of emitting a certain sound? What is the
physical cause of this difference? At first I thought it might be
ascribed to the period of life, when the worms that are to become queens
receive the royal food. While hives swarm, the royal worms receive the
food adapted for queens, from the moment of leaving the egg; those on
the contrary, destined for queens, according to M. Schirach's method,
receive it only the second or third day of their existence. It appears
to me that this circumstance may have an influence on the different
parts of organisation, and particularly on the organ of voice.
Experiment has not confirmed this conjecture. I constructed glass cells
in perfect imitation of royal cells, that the metamorphosis of the worms
into nymphs, and of the nymphs to queens, might be visible. These
experiments are related in a preceding letter. Into one of these
artificial cells we introduced the nymph of a worm, reared according to
M. Schirach's method, twenty-four hours before it could naturally
undergo its last metamorphosis; and we replaced the glass cell in the
hive, that the nymph might have the necessary degree of heat. Next day,
we had the satisfaction of seeing it divest itself of the spoil, and
assume its ultimate figure. This queen was prevented from escaping from
her prison; but we had contrived an aperture for her thrusting out her
trunk, and that the bees might feed her. I expected that she would have
been completely mute; but it was otherwise; for she emitted sounds
similar to those already described, therefore my conjecture was
erroneous.
I next conceived that the queen being restrained in her motions, and in
her desire for liberty, was induced to emit certain sounds. All queens,
in this new point of view, are equally capable of emitting the sound,
but to induce them to it, they must be in a confined situation. In the
natural state, the queens that come from workers are not a single
instant in restraint; and, if they do not emit the sound, it is because
nothing impels them to it. On the other hand, those produced at the time
of swarming are induced to do so by the captivity in which they are
kept. For my own part, I give little weight to this conjecture; and
though I state it here, it is less with a view to claim merit than to
put others on a plan of discovering something more probable.
I do not ascribe to myself the credit of having discovered the humming
of the queen bee. Old authors speak of it. M. de Reaumur cites a Latin
work published 1671, _Monarchia Femina_, by Charles Butler. He gives a
very brief abstract of this naturalist's observations, who we easily see
has exaggerated or rather disguised the truth, by mixing it with the
most absurd fancies; but it is not the less evident that Butler has
heard this peculiar humming of queens, and that he did not confound it
with the confused humming sometimes heard in hives.
Fourthly. _The young queens conducting swarms from their native hive are
still in a virgin state._ The day after, being settled in their new
abode, they generally depart in quest of the males; and this is usually
the fifth day of their existence as queens; for two or three pass in
captivity, one in their native hive, and a fifth in their new dwelling.
Those queens that come from the worm of a worker, also pass five days in
the hive before going in quest of males. So long as in a state of
virginity, both are treated with indifference by the bees; but after
returning with the external marks of fecundation, they are received by
their subjects with the most distinguished respect. However, forty-six
hours elapse after fecundation before they begin to lay. The old queen,
which leads the first swarm in spring, requires no farther commerce with
the males, for preservation of her fecundity. A single copulation is
sufficient to impregnate all the eggs she will lay for at least two
years.
_PREGNY, 8. September 1791._
FOOTNOTES:
{M} Schirach seems to have been aware of this fact.--T.
LETTER XI.
_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° and 97°, in a fine day
of spring; but during the tumult which precedes swarming, it rises above
104°. 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 larvæ 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.