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 larvæ, 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._
LETTER XII.
_ADDITIONAL OBSERVATIONS ON QUEENS THAT LAY ONLY THE EGGS OF DRONES, AND
ON THOSE DEPRIVED OF THE ANTENNÆ._
In relating my first observations on queens that lay male eggs alone, I
have proved that they lay them in cells of all dimensions indifferently,
and even in royal cells. It is also proved that the same treatment is
given to male worms hatched from eggs laid in the royal cells, as if
they were actually to be transformed to queens; and I have added, that
in this instance the instinct of the workers appeared defective. It is
indeed most singular, that bees which know the worms of males so well
when the eggs are laid in small cells, and never fail to give them a
convex covering when about to transform to nymphs, should no longer
recognise the same species of worms when the eggs are laid in royal
cells, and treat them exactly as if they should change to queens. This
irregularity depends on something I cannot comprehend.
In revising what is said on this subject, I observe still wanting an
interesting experiment to complete the history of queens that lay only
the eggs of drones. I had to investigate whether these females could
themselves distinguish that the eggs they deposit in the royal cells
would not produce queens. I have already observed that they do not
endeavour to destroy these cells when close, and I thence concluded,
that in general the presence of royal cells in their hive does not
inspire them with the same aversion to females whose fecundation has
been retarded; but to ascertain the fact more correctly, it was
essential to examine how the presence of a cell containing a royal nymph
would affect a queen that had never laid any other than the eggs of
drones.
This experiment was easy; and I put it in practice on the fourth of
September, in a hive some time deprived of its queen. The bees had not
failed to construct several royal cells for replacing their females. I
chose this opportunity for supplying them with a queen, whose
fecundation had been retarded to the twenty-eighth day, and which laid
none but the eggs of males. At the same time, I removed all the royal
cells, except one that had been sealed five days. One remaining was
enough to shew the impression it would make on the stranger queen
introduced; had she endeavoured to destroy it; this, in my opinion,
would have proved that she anticipated the origin of a dangerous rival.
You must admit the use I make of the word anticipate; it saves a long
paraphrase; I feel the impropriety of it. If, on the contrary, she did
not attack the cell I would thence conclude that the delay of
fecundation, which deprived her of the power of laying workers eggs, had
also impaired her instinct. This was the fact; the queen passed several
times over the royal cell, both the first and the subsequent day,
without seeming to distinguish it from the rest. She quietly laid in the
surrounding cells; notwithstanding the cares incessantly bestowed by the
bees upon it, she never one moment appeared to suspect the danger with
which the included royal nymph threatened her. Besides, the workers
treated their new queen as well as they would have treated any other
female. They were lavish of honey and respect, and formed those regular
circles around her that seem an expression of homage.
Thus, independent of the derangement occasioned by retarded
impregnation, in the sexual organs of queens, it certainly impairs their
instinct. Aversion or jealousy is no longer preserved against their own
sex in the nymphine state, nor do they longer endeavour to destroy them
in their cradles.
My readers will be surprised that queens whose fecundation has been
retarded, and whose fecundity is so useless to bees, should be so well
treated and become as dear to them as females laying both kinds of eggs.
But I remember to have observed a fact more astonishing still. I have
seen workers bestow every attention on a queen though sterile; and after
her death treat her dead body as they had treated herself when alive,
and long prefer this inanimate body to the most fertile queens I had
offered them. This sentiment, which assumes the appearance of so lively
an affection, is probably the effect of some agreeable sensation
communicated to bees by their queen, independent of fertility. Those
laying only the eggs of males probably excite the same sensation in the
workers.
I now recollect that the celebrated Swammerdam somewhere observes, that
when a queen is blind, sterile, or mutilated, she ceases to lay, and the
workers of her hive no longer labour or make any collections, as if
aware that it was now useless to work. He cites no experiment that led
him to the discovery. Those made by myself have afforded some very
singular results.
I frequently amputated the four wings of queens; and not only did they
continue laying, but the same confederation of them was testified by the
workers as before. Therefore, Swammerdam has no foundation for
asserting, that mutilated queens cease to lay. Indeed, from his
ignorance of fecundation taking place without the hives, it is possible
he cut the wings off virgin queens, and they, becoming incapable of
flight, remained sterile from inability to seek the males in the air.
Thus, amputation of the wings does not produce sterility in queens.
* * * * *
I have frequently cut off one antennæ to recognise a queen the more
easily, and it was not prejudicial to her either in fecundity or
instinct nor did it affect the attention paid to her by the bees. It is
true, that as one still remained, the mutilation was imperfect; and the
experiment decided nothing. But amputation of both antennæ produced most
singular effects. On the fifth of September, I cut both off a queen that
laid the eggs of males only, and put her into the hive immediately after
the operation. From this moment there was a great alteration in her
conduct. She traversed the combs with extraordinary vivacity. Scarcely
had the workers time to separate and recede before her; she dropped her
eggs, without attending to deposit them in any cell. The hive not being
very populous, part was without comb. Hither she seemed particularly
earnest to repair, and long remained motionless. She appeared to avoid
the bees; however, several workers followed her into this solitude, and
treated her with the most evident respect. She seldom required honey
from them, but, when that occurred, directed her trunk with an uncertain
kind of feeling, sometimes on the head and sometimes on the limbs of the
workers, and if it did reach their mouths, it was by chance. At other
times she returned upon the combs, then quitted them to traverse the
glass sides of the hive: and always dropped eggs during her various
motions. Sometimes she appeared tormented with the desire of leaving her
habitation. She rushed towards the opening, and entered the glass tube
adapted there; but the external orific being too small, after fruitless
exertion, she returned. Notwithstanding these symptoms of delirium, the
bees did not cease to render her the same attention as they ever pay to
their queens, but this one received it with indifference. All that I
describe appeared to me the consequence of amputating the antennæ.
However, her organization having already suffered from retarded
fecundation, and as I had observed her instinct in some degree impaired,
both causes might possibly concur in producing the same effect. To
distinguish properly what belonged to the privation of the antennæ, a
repetition of the experiment was necessary, in a queen otherwise well
organised, and capable of laying both kinds of eggs.
This I did on the sixth of September. I amputated both the antennæ of a
female which had been several months the subject of observation, and
being of great fecundity had already laid a considerable number of
workers eggs, and those of males. I put her into the same hive where the
queen of the preceding experiment still remained, and she exhibited
precisely the same marks of delirium and agitation, which I think it
needless to repeat. I shall only add, that to judge better of the
effect produced by privation of the antennæ, on the industry and
instinct of bees, I attentively considered the manner in which these two
mutilated queens treated each other. You cannot have forgot, Sir, the
animosity with which queens, possessing all their organs, combat, on
which account it became extremely interesting to learn whether they
would experience the same reciprocal aversion after losing their
antennæ. We studied these queens a long time; they met several times in
their courses, and without exhibiting the smallest resentment. This last
instance is, in my opinion, the most complete evidence of a change
operated in their instinct.
Another very remarkable circumstance, which this experiment gave me
occasion to observe, consists in the good reception given by the bees to
the stranger queen, while they still preserved the first. Having so
often seen the symptoms of discontent that a plurality of queens
occasions, after having witnessed the clusters formed around these
supernumerary queens to confine them, I could not expect they would pay
the same homage to a second mutilated one they still testified towards
the first. Is it because after losing the antennæ, these queens have no
more any characteristic which distinguishes the one from the other?
I was the more inclined to admit this conjecture from the bad reception
of a third fertile queen preserving her antennæ, which was introduced
into the same hive. The bees seized, bit her, and confined her so
closely, that she could hardly breath or move. Therefore, if they treat
two females deprived of antennæ in the same hive equally well, it is
probably because they experience the same sensation from these two
females, and want the means of longer distinguishing them from each
other.
From all this, I conclude, that the antennæ are not a frivolous ornament
to insects, but, according to all appearance, are the organs of touch
or smell. Yet I cannot affirm which of these senses reside in them. It
is not impossible that they are organised in such a manner as to fulfil
both functions at once.
As in the course of this experiment both mutilated females constantly
endeavoured to escape from the hive, I wished to see what they would do
if set at liberty, and whether the bees would accompany them in their
flight. Therefore I removed the first and third queen from the hive,
leaving the fertile mutilated one, and enlarged the entrance.
The queen left her habitation the same day. At first she tried to fly,
but, her belly being full of eggs, she fell down and never attempted it
again. No workers accompanied her. Why, after rendering the queen so
much attention while she lived among them, did they abandon her now on
her departure? You know, Sir, that queens governing a weak swarm are
sometimes discouraged, and fly away, carrying all their little colony
along with them. In like manner sterile queens, and those whose dwelling
is ravaged by weevils, depart; and are followed by all their bees. Why
therefore in this experiment did the workers allow their mutilated queen
to depart alone? All that I can hazard on this question is a conjecture.
It appears that bees are induced to quit the hives from the increased
heat which occasions the agitation of their queen, and the tumultuous
motion which she communicates to them. A mutilated queen,
notwithstanding her delirium, does not agitate the workers, because she
seeks the uninhabited parts of the hive, and the glass panes of it: she
hurries over clusters of bees, but the shock resembles that of any other
body, and produces only a local and instantaneous motion. The agitation
arising from it, is not communicated from one place to another, like
that produced by a queen, which in the natural state wishes to abandon
her hive and lead out a swarm; there is no increased heat, consequently
nothing that renders the hive insupportable to her.
This conjecture, which affords a tolerable explanation why bees persist
in remaining in the hive, though the mutilated queen has left it, is no
reason for the motive inducing the queen herself to depart. Her instinct
is altered; that is the whole that I can perceive. I can discern nothing
more. It is very fortunate for the hive, that this queen departs, for
the bees incessantly attend her; nor do they ever think of procuring
another while she remains; and if she was long of leaving them, it would
be impossible to replace her; for the workers worms would exceed the
term at which they are convertible into royal worms, and the hive would
perish. Observe, that the eggs dropped by the mutilated queen can never
serve for replacing her, for, not being deposited in cells, they dry and
produce nothing.
I have yet to say a few words on females laying male eggs only. M.
Schirach supposes that one branch of their double ovary suffers some
alteration. He seems to think that one of these branches contains the
eggs of males, while the other has none but common eggs, and as he
ascribes the inability of certain queens to lay the latter to some
disease, his conjecture becomes very plausible. In fact, if the eggs of
males and workers are indiscriminately mixed in both branches of the
ovary, it appears at first sight that whatever cause acts on that organ,
it should equally affect both species of eggs. If on the contrary, one
branch is occupied by the eggs of drones only, and the other contains
none but common eggs, we may conceive how disease affects the one, while
the other remains untouched. Though this conjecture is probable, it is
confuted by observation. We lately dissected queens, which laid none but
male eggs, and found both branches of the ovary equally well expanded,
and equally sound, if I may use the expression. The only difference
that struck us was that in these two branches, the eggs were apparently
not so close together as in the ovaries of queens laying both kinds of
eggs.
_PREGNY, 12. September 1791._
LETTER XIII.
_ECONOMICAL CONSIDERATIONS ON BEES._
In this letter I shall treat of the advantages that may be derived from
the new invented hives, called _book_ or _leaf_ hives, in promoting the
_economical knowledge_ of bees.
It is needless to relate the different methods hitherto employed in
forcing bees to yield up a portion of their honey and wax; all resemble
each other in being cruel and ill understood.
It is evident, when bees are cultivated for the purpose of sharing the
produce of their labours, we must endeavour to multiply them as much as
the nature of the country admits; and consequently to regard their lives
at the time we plunder them. Therefore it is an absurd custom to
sacrifice whole hives to get at the riches they contain. The inhabitants
of this country, who follow no other method, annually lose immense
numbers of hives; and spring, being generally unfavourable to swarms,
the loss is irreparable. I well know that at first they will not adopt
any other method; they are too much attached to prejudices and old
customs. But naturalists and intelligent cultivators of bees will be
sensible of the utility of the method I propose; and if they apply it to
use I hope their example will extend and perfect the culture of bees.
It is not more difficult to lodge a natural swarm in a leaf hive than in
any other of a different shape. But there is one precaution essential
to success, which I should not omit. Though the bees are indifferent as
to the position of their combs, and as to their greater or lesser size,
they are obliged to construct them perpendicular to the horizon, and
parallel to each other. Therefore, if left entirely to themselves, when
establishing a colony in one of those new hives, they would frequently
construct several small combs parallel indeed, but perpendicular to the
plane of the frames or leaves, and by this disposition prevent the
advantages which I think to derive from the figure of my hives, since
they could not be opened without breaking the combs. Thus they must
previously have a guide to follow; the cultivator himself lays the
foundation of their edifices, and that by a simple method. A portion of
comb must be solidly fixed in some of the boxes composing the hive; the
bees will extend it; and, in prosecution of their work, will accurately
follow the plan already given them. Therefore on opening the hive, no
obstacle is to be removed, nor stings to be dreaded, for one of the
most singular and valuable properties attending this construction, is
its rendering the bees tractable. I appeal to you, Sir, for the truth of
what I say. In your presence I have opened all the divisions of the most
populous hives, and the tranquillity of the bees has given you great
surprise. I can desire no other evidence of my assertion. It is in the
facility of opening these hives at pleasure that all the advantages lie,
which I expect in perfecting the economical knowledge of bees.
I conceive, when I observe bees may be rendered tractable, that it need
not be added, I do not arrogate to myself the absurd pretence of
_taming_ them, for this excites a vague idea of tricks; and I would
willingly avoid the hazard of exposing myself to any such reproach. I
ascribe their tranquillity on opening the hives, to the manner that the
sudden introduction of light affects them; then, they seem rather to
testify fear than anger. Many retire and enter the cells, and appear to
conceal themselves. What confirms my conjecture is, their being less
tractable during night or after sunset than through the day. Thus, we
must open the hives, while the sun is above the horizon, cautiously, and
without any sudden shock. The divisions must be separated slowly, and
care taken not to wound any of the bees. If they cluster too much on the
combs, they must be brushed off with a feather; and breathing on them
carefully avoided. The air we expire seems to excite their fury; it
certainly has some irritating quality, for if bellows are used, they are
rather disposed to escape than to sting.
Respecting the advantages of leaf hives, I shall observe, they are very
convenient for forming _artificial_ swarms. In the history of natural
swarms, I have shewn how many favourable circumstances are necessary for
their success. From experience I know that they very often fail in our
climate; and even when a hive is disposed to swarm, it frequently
happens that the swarm is lost either because the moment of its
departure has not been foreseen, because it rises out of sight, or
settles on inaccessible places. Instructing the cultivators of bees how
to make artificial swarms is a real service, and the form of my hives
renders this an easy operation. But it requires farther illustration.
Since bees, according to M. Schirach's discovery, can procure another
queen after having lost their own, provided there is workers brood in
the combs not above three days old, it results that we can at pleasure
produce queens, by removing the reigning one. Therefore, if a hive
sufficiently populous is divided in two, one half will retain the old
queen, and the other will not be long of obtaining a new one. But to
ensure success, we must choose a propitious moment, which is never
certain but in leaf hives. In these we can see whether the population is
sufficient to admit of division, if the brood is of the proper age, if
males exist or are ready to be produced for impregnating the young
queens.
Supposing the union of all these conditions, the following is the method
to be pursued. The leaf hive may be divided through the middle without
any shock. Two empty divisions may be insinuated between the halves,
which, when exactly applied to each other, are close on the outside. The
queen must be sought in one of the halves, and marked to avoid mistake.
If she by chance remains in the division with most brood, she is to be
transferred to the other with less, that the bees may have every
possible opportunity of obtaining another female. Next, it is necessary
to connect the halves together, by a cord tied tight around them, and
care must be taken that they are set on the same board that the hive
previously occupied. The old entrance, now become useless, will be shut
up; but as each half requires a new one, it ought to be made at the
bottom of each division, on purpose that they may be as far asunder as
possible. Both entrances should not be made on the same day. The bees in
the half deprived of the queen ought to be confined twenty-four hours,
and no opening made before then except for admission of air. Without
this precaution, they would soon search for their queen, and infallibly
find her in the other division. They will then retire in great numbers
from their own division, until too few remain to perform the necessary
labours. But this will not ensue if they are confined twenty-four hours,
provided that interval is sufficient to make them forget the queen. When
all these circumstances are favourable, the bees, in the division
wanting the queen, will the same day begin to labour in procuring
another, and ten or fifteen days after the operation, their loss will be
repaired. The young female they have reared, soon issues forth to seek
impregnation, and in two days commences the laying of workers eggs.
Nothing more is wanting to the bees of this half hive, and the success
of the artificial swarm is ensured.