The Mason-bees
by
J. Henri Fabre
Part 3 out of 4
here and there, cases occur in which the animal harmonizes with
surrounding objects. It would even be very strange if such cases were
excluded from actuality, since everything is possible. But these rare
coincidences are faced, under exactly similar conditions, by
inconsistencies so strongly marked and so numerous that, having
frequency on their side, they ought, in all logic, to serve as the
basis of the law. Here, one fact says yes; there, a thousand facts say
no. To which evidence shall we lend an ear? If we only wish to bolster
up a theory, it would be prudent to listen to neither. The how and why
escapes us; what we dignify with the pretentious title of a law is but
a way of looking at things with our mind, a very squint-eyed way,
which we adopt for the requirements of our case. Our would-be laws
contain but an infinitesimal shade of reality; often indeed they are
but puffed out with vain imaginings. Such is the law of mimesis, which
explains the Green Grasshopper by the green leaves in which this
Locust settles and is silent as to the Crioceris, that coral-red
Beetle who lives on the no less green leaves of the lily.
And it is not only a mistaken interpretation: it is a clumsy pitfall
in which novices allow themselves to be caught. Novices, did I say?
The greatest experts themselves fall into the trap. One of our masters
of entomology did me the honour to visit my laboratory. I was showing
my collection of parasites. One of them, clad in black and yellow,
attracted his attention.
'This,' said he, 'is obviously a parasite of the Wasps.'
Surprised at the statement, I interposed:
'By what signs do you know her?'
'Why look: it's the exact colouring of the Wasp, a mixture of black
and yellow. It is a most striking case of mimesis.'
'Just so; nevertheless, our black-and-yellow friend is a parasite of
the Chalicodoma of the Walls, who has nothing in common, either in
shape or colour, with the Wasp. This is a Leucopsis, not one of whom
enters the Wasps' nest.'
'Then mimesis...?'
'Mimesis is an illusion which we should do well to relegate to
oblivion.'
And, with the evidence, a whole series of conclusive examples, in
front of him, my learned visitor admitted with a good grace that his
first convictions were based on a most ludicrous foundation.
A piece of advice to beginners: you will go wrong a thousand times for
once that you are right if, when anxious to obtain a premature sight
of the probable habits of an insect, you take mimesis as your guide.
With mimesis above all, it is wise, when the law says that a thing is
black, first to enquire whether it does not happen to be white.
Let us go on to more serious subjects and enquire into parasitism
itself, without troubling any longer about the costume of the
parasite. According to etymology, a parasite is one who eats another's
bread, one who lives on the provisions of others. Entomology often
alters this term from its real meaning. Thus it describes as parasites
the Chrysis, the Mutilla, the Anthrax, the Leucopsis, all of whom feed
their family not on the provisions amassed by others, but on the very
larvae which have consumed those provisions, their actual property.
When the Tachinae have succeeded in laying their eggs on the game
warehoused by the Bembex, the burrower's home is invaded by real
parasites, in the strict sense of the word. Around the heap of Gad-
flies, collected solely for the children of the house, new guests
force their way, numerous and hungry, and without the least ceremony
plunge into the thick of it. They sit down to a table that was not
laid for them; they eat side by side with the lawful owner; and this
in such haste that he dies of starvation, though he is respected by
the teeth of the interlopers who have gorged themselves on his
portion.
When the Melecta has substituted her egg for the Anthophora's, here
again we see a real parasite settling in the usurped cell. The pile of
honey laboriously gathered by the mother will not even be broken in
upon by the nurseling for which it was intended. Another will profit
by it, with none to say him nay. Tachinae and Melectae: those are the
true parasites, consumers of others' goods.
Can we say as much of the Chrysis or the Mutilla? In no wise. The
Scoliae, whose habits are known to us, are certainly not parasites.
(The habits of the Scolia-wasp have been described in different essays
not yet translated into English.--Translator's Note.) No one will
accuse them of stealing the food of others. Zealous workers, they seek
and find under ground the fat grubs on which their family will feed.
They follow the chase by virtue of the same quality as the most
renowned hunters, Cerceris, Sphex or Ammophila; only, instead of
removing the game to a special lair, they leave it where it is, down
in the burrow. Homeless poachers, they let their venison be consumed
on the spot where it is caught.
In what respect do the Mutilla, the Chrysis, the Leucopsis, the
Anthrax and so many others differ, in their way of living, from the
Scolia? It seems to me, in none. See for yourselves. By an artifice
that varies according to the mother's talent, their grubs, either in
the germ-stage or newly-born, are brought into touch with the victim
that is to feed them: an unwounded victim, for most of them are
without a sting; a live victim, but steeped in the torpor of the
coming transformations and thus delivered without defence to the grub
that is to devour it.
With them, as with the Scoliae, meals are made on the spot on game
legitimately acquired by indefatigable battues or by patient stalking
in which all the rules have been observed; only, the animal hunted is
defenceless and does not need to be laid low with a dagger-thrust. To
seek and find for one's larder a torpid prey incapable of resistance
is, if you like, less meritorious than heroically to stab the strong-
jawed Rose-chafer or Rhinoceros-beetle; but since when has the title
of sportsman been denied to him who blows out the brains of a harmless
Rabbit, instead of waiting without flinching for the furious charge of
the Wild Boar and driving his hunting-knife into him behind his
shoulder? Besides, if the actual assault is without danger, the
approach is attended with a difficulty that increases the merit of
these second-rate poachers. The coveted game is invisible. It is
confined in the stronghold of a cell and moreover protected by the
surrounding wall of a cocoon. Of what prowess must not the mother be
capable to determine the exact spot at which it lies and to lay her
egg on its side or at least close by? For these reasons, I boldly
number the Chrysis, the Mutilla and their rivals among the hunters and
reserve the ignoble title of parasites for the Tachina, the Melecta,
the Crocisa, the Meloe-beetle, in short, for all those who feed on the
provisions of others.
All things considered, is ignoble the right epithet to apply to
parasitism? No doubt, in the human race, the idler who feeds at other
people's tables is contemptible at all points; but must the animal
bear the burden of the indignation inspired by our own vices? Our
parasites, our scurvy parasites, live at their neighbour's expense:
the animal never; and this changes the whole aspect of the question. I
know of no instance, not one, excepting man, of parasites who consume
the provisions hoarded by a worker of the same species. There may be,
here and there, a few cases of larceny, of casual pillage among
hoarders belonging to the same trade: that I am quite ready to admit,
but it does not affect things. What would be really serious and what I
formally deny is that, in the same zoological species, there should be
some who possessed the attribute of living at the expense of the rest.
In vain do I consult my memory and my notes: my long entomological
career does not furnish me with a solitary example of such a misdeed
as that of an insect leading the life of a parasite upon its fellows.
When the Chalicodoma of the Sheds works, in her thousands, at her
Cyclopean edifice, each has her own home, a sacred home where not one
of the tumultuous swarm, except the proprietress, dreams of taking a
mouthful of honey. It is as though there were a neighbourly
understanding to respect the others' rights. Moreover, if some
heedless one mistakes her cell and so much as alights on the rim of a
cup that does not belong to her, forthwith the owner appears,
admonishes her severely and soon calls her to order. But, if the store
of honey is the estate of some deceased Bee, or of some wanderer
unduly prolonging her absence, then--and then alone--a kinswoman
seizes upon it. The goods were waste property, which she turns to
account; and it is a very proper economy. The other Bees and Wasps
behave likewise: never, I say never, do we find among them an idler
assiduously planning the conquest of her neighbour's possessions. No
insect is a parasite on its own species.
What then is parasitism, if one must look for it among animals of
different races? Life in general is but a vast brigandage. Nature
devours herself; matter is kept alive by passing from one stomach into
another. At the banquet of life, each is in turn the guest and the
dish; the eater of to-day becomes the eaten of tomorrow; hodie tibi,
cras mihi. Everything lives on that which lives or has lived;
everything is parasitism. Man is the great parasite, the unbridled
thief of all that is fit to eat. He steals the milk from the Lamb, he
steals the honey from the children of the Bee, even as the Melecta
pilfers the pottage of the Anthophora's sons. The two cases are
similar. Is it the vice of indolence? No, it is the fierce law which
for the life of the one exacts the death of the other.
In this implacable struggle of devourers and devoured, of pillagers
and pillaged, of robbers and robbed, the Melecta deserves no more than
we the title of ignoble; in ruining the Anthophora, she is but
imitating man in one detail, man who is the infinite source of
destruction. Her parasitism is no blacker than ours: she has to feed
her offspring; and, possessing no harvesting-tools, ignorant besides
of the art of harvesting, she uses the provisions of others who are
better endowed with implements and talents. In the fierce riot of
empty bellies, she does what she can with the gifts at her disposal.
CHAPTER 9. THE THEORY OF PARASITISM.
The Melecta does what she can with the gifts at her disposal. I should
leave it at that, if I had not to take into consideration a grave
charge brought against her. She is accused of having lost, for want of
use and through laziness, the workman's tools with which, so we are
told, she was originally endowed. Finding it to her advantage to do
nothing, bringing up her family free of expense, to the detriment of
others, she is alleged to have gradually inspired her race with an
abhorrence for work. The harvesting-tools, less and less often
employed, dwindled and perished as organs having no function; the
species changed into a different one; and finally idleness turned the
honest worker of the outset into a parasite. This brings us to a very
simple and seductive theory of parasitism, worthy to be discussed with
all respect. Let us set it forth.
Some mother, nearing the end of her labours and in a hurry to lay her
eggs, found, let us suppose, some convenient cells provisioned by her
fellows. There was no time for nest-building and foraging; if she
would save her family, she must perforce appropriate the fruit of
another's toil. Thus relieved of the tedium and fatigue of work, freed
of every care but that of laying eggs, she left a progeny which duly
inherited the maternal slothfulness and handed this down in its turn,
in a more and more accentuated form, as generation followed on
generation; for the struggle for life made this expeditious way of
establishing yourself one of the most favourable conditions for the
success of the offspring. At the same time, the organs of work, left
unemployed, became atrophied and disappeared, while certain details of
shape and colouring were modified more or less, so as to adapt
themselves to the new circumstances. Thus the parasitic race was
definitely established.
This race, however, was not too greatly transformed for us to be able,
in certain cases, to trace its origin. The parasite has retained more
than one feature of those industrious ancestors. So, for instance, the
Psithyrus is extremely like the Bumble-bee, whose parasite and
descendant she is. The Stelis preserves the ancestral characteristics
of the Anthidium; the Coelioxys-bee recalls the Leaf-cutter.
Thus speak the evolutionists, with a wealth of evidence derived not
only from correspondence in general appearance, but also from
similarity in the most minute particulars. Nothing is small: I am as
much convinced of that as any man; and I admire the extraordinary
precision of the details furnished as a basis for the theory. But am I
convinced? Rightly or wrongly, my turn of mind does not hold minutiae
of structure in great favour: a joint of the palpi leaves me rather
cold; a tuft of bristles does not appear to me an unanswerable
argument. I prefer to question the creature direct and to let it
describe its passions, its mode of life, its aptitudes. Having heard
its evidence, we shall see what becomes of the theory of parasitism.
Before calling upon it to speak, why should I not say what I have on
my mind? And mark me, first of all, I do not like that laziness which
is said to favour the animal's prosperity. I have also believed and I
still persist in believing that activity alone strengthens the present
and ensures the future both of animals and men. To act is to live; to
work is to go forward. The energy of a race is measured by the
aggregate of its action.
No, I do not like it at all, this idleness so much commended of
science. We have quite enough of these zoological brutalities: man,
the son of the Ape; duty, a foolish prejudice; conscience, a lure for
the simple; genius, neurosis; patriotism, jingo heroics; the soul, a
product of protoplasmic energies; God, a puerile myth. Let us raise
the war-whoop and go out for scalps; we are here only to devour one
another; the summum bonum is the Chicago packer's dollar-chest!
Enough, quite enough of that, without having transformism next to
break down the sacred law of work. I will not hold it responsible for
our moral ruin; it has not a sturdy enough shoulder to effect such a
breach; but still it has done its worst.
No, once more, I do not like those brutalities which, denying all that
gives some dignity to our wretched life, stifle our horizon under an
extinguisher of matter. Oh, don't come and forbid me to think, though
it were but a dream, of a responsible human personality, of
conscience, of duty, of the dignity of labour! Everything is linked
together: if the animal is better off, as regards both itself and its
race, for doing nothing and exploiting others, why should man, its
descendant, show greater scruples? The principle that idleness is the
mother of prosperity would carry us far indeed. I have said enough on
my own account; I will call upon the animals themselves, more eloquent
than I.
Are we so very sure that parasitic habits come from a love of
inaction? Did the parasite become what he is because he found it
excellent to do nothing? Is repose so great an advantage to him that
he abjured his ancient customs in order to obtain it? Well, since I
have been studying the Bee who endows her family with the property of
others, I have not yet seen anything in her that points to
slothfulness. On the contrary, the parasite leads a laborious life,
harder than that of the worker. Watch her on a slope blistered by the
sun. How busy she is, how anxious! How briskly she covers every inch
of the radiant expanse, how indefatigable she is in her endless
quests; in her visits, which are generally fruitless! Before coming
upon a nest that suits her, she has dived a hundred times into
cavities of no value, into galleries not yet victualled. And then,
however kindly her host, the parasite is not always well received in
the hostelry. No, it is not all roses in her trade. The expenditure of
time and labour which she finds necessary in order to house an egg may
easily equal or even exceed that of the worker in building her cell
and filling it with honey. That industrious one has regular and
continuous work, an excellent condition for success in her egg-laying;
the other has a thankless and precarious task, at the mercy of a
thousand accidents which endanger the great undertaking of installing
the eggs. One has only to watch the prolonged hesitation of a
Coelioxys seeking for the Leaf-cutters' cells to recognize that the
usurpation of another's nest is not effected without serious
difficulties. If she turned parasite in order to make the rearing of
her offspring easier and more prosperous, certainly she was very ill-
inspired. Instead of rest, hard work; instead of a flourishing family,
a meagre progeny.
To generalities, which are necessarily vague, we will add some precise
facts. A certain Stelis (Stelis nasuta, LATR.) is a parasite of the
Mason-bee of the Walls. When the Chalicodoma has finished building her
dome of cells upon her pebble, the parasite appears, makes a long
inspection of the outside of the home and proposes, puny as she is, to
introduce her eggs into this cement fortress. Everything is most
carefully closed: a layer of rough plaster, at least two-fifths of an
inch thick, entirely covers the central accumulation of cells, which
are each of them sealed with a thick mortar plug. And it is the honey
of these well-guarded chambers that has to be reached by piercing a
wall almost as hard as rock.
The parasite pluckily sets to; the idler becomes a glutton for work.
Atom by atom, she perforates the general enclosure and scoops out a
shaft just sufficient for her passage; she reaches the lid of the cell
and gnaws it until the coveted provisions appear in sight. It is a
slow and painful process, in which the feeble Stelis wears herself
out, for the mortar is much the same as Roman cement in hardness. I
myself find a difficulty in breaking it with the point of my knife.
What patient effort, then, the task requires from the parasite, with
her tiny pincers!
I do not know exactly how long the Stelis takes to make her entrance-
shaft, as I have never had the opportunity or rather the patience to
follow the work from start to finish; but what I do know is that a
Chalicodoma of the Walls, incomparably larger and stronger than the
parasite, when demolishing before my eyes the lid of a cell sealed
only the day before, was unable to complete her undertaking in one
afternoon. I had to come to her assistance in order to discover,
before the end of the day, the object of her housebreaking. When the
Mason-bee's mortar has once set, its resistance is that of stone. Now
the Stelis has not only to pierce the lid of the honey-store; she must
also pierce the general casing of the nest. What a time it must take
her to get through such a task, a gigantic one for her poor tools!
It is done at last, after infinite labour. The honey appears. The
Stelis slips through and, on the surface of the provisions, side by
side with the Chalicodoma's eggs, the number varying from time to
time. The victuals will be the common property of all the new
arrivals, whether the son of the house or strangers.
The violated dwelling cannot remain as it is, exposed to marauders
from without; the parasite must herself wall up the breach which she
has contrived. The quondam housebreaker becomes a builder. At the foot
of the pebble, the Stelis collects a little of that red earth which
characterizes our stony plateaus grown with lavender and thyme; she
makes it into mortar by wetting it with saliva; and with the pellets
thus prepared she fills up the entrance-shaft, displaying all the care
and art of a regular master-mason. Only, the work clashes in colour
with the Chalicodoma's. The Bee goes and gathers her cementing-powder
on the adjoining high-road, the metal of which consists of broken
flint-stones, and very seldom uses the red earth under the pebble
supporting the nest. This choice is apparently dictated by the fact
that the chemical properties of the former are more likely to produce
a solid structure. The lime of the road, mixed with saliva, yields a
harder cement than red clay would do. At any rate, the Chalicodoma's
nest is more or less white because of the source of its materials.
When a red speck, a few millimetres wide, appears on this pale
background, it is a sure sign that a Stelis has been that way. Open
the cell that lies under the red stain: we shall find the parasite's
numerous family established there. The rusty spot is an infallible
indication that the dwelling has been violated: at least, it is so in
my neighbourhood, where the soil is as I have described.
We see the Stelis, therefore, at first a rabid miner, using her
mandibles against the rock; next a kneader of clay and a plasterer
restoring broken ceilings. Her trade does not seem one of the least
arduous. Now what did she do before she took to parasitism? Judging
from her appearance, the transformists tell us that she was an
Anthidium, that is to say, she used to gather the soft cotton-wool
from the dry stalks of the lanate plants and fashion it into wallets,
in which to heap up the pollen-dust which she gleaned from the flowers
by means of a brush carried on her abdomen. Or else, springing from a
genus akin to the cotton-workers, she used to build resin partitions
in the spiral stairway of a dead Snail. Such was the trade driven by
her ancestors.
Really! So, to avoid slow and painful work, to achieve an easy life,
to give herself the leisure favourable to the settlement of her
family, the erstwhile cotton-presser or collector of resin-drops took
to gnawing hardened cement! She who once sipped the nectar of flowers
made up her mind to chew concrete! Why, the poor wretch toils at her
filing like a galley-slave! She spends more time in ripping up a cell
than it would take her to make a cotton wallet and fill it with food.
If she really meant to progress, to do better in her own interest and
that of her family, by abandoning the delicate occupations of the old
days, we must confess that she has made a strange mistake. The mistake
would be no greater if fingers accustomed to fancy-weaving were to lay
aside velvet and silk and proceed to handle the quarryman's blocks or
to break stones on the roadside.
No, the animal does not commit the folly of voluntarily embittering
its lot; it does not, in obedience to the promptings of idleness, give
up one condition to embrace another and a more irksome; should it
blunder for once, it will not inspire its posterity with a wish to
persevere in a costly delusion. No, the Stelis never abandoned the
delicate art of cotton-weaving to break down walls and to grind
cement, a class of work far too unattractive to efface the memory of
the joys of harvesting amid the flowers. Indolence has not evolved her
from an Anthidium. She has always been what she is to-day: a patient
artificer in her own line, a steady worker at the task that has fallen
to her share.
That hurried mother who first, in remote ages, broke into the abode of
her fellows to secure a home for her eggs found this unscrupulous
method, so you tell us, very favourable to the success of her race, by
virtue of its economy of time and trouble. The impression left by this
new policy was so profound that heredity bequeathed it to posterity,
in ever-increasing proportions, until at last parasitic habits became
definitely fixed. The Chalicodoma of the Sheds, followed by the Three-
horned Osmia, will teach us what to think of this conjecture.
I have described in an earlier chapter my installation of Chalicodoma-
hives against the walls of a porch facing the south. Here, on a level
with my head, placed so that they can easily be observed, hang some
tiles removed from the neighbouring roofs in winter, together with
their enormous nests and their occupants. Every May, for five or six
years in succession, I have assiduously watched the works of my Mason-
bees. From the mass of my notes on the subject I take the following
experiments which bear upon the matter under discussion.
Long ago, when I used to scatter a handful of Chalicodomae some way
from home, in order to study their capacity for finding their nest
again, I noticed that, if they were too long absent, the laggards
found their cells closed on their return. Neighbours had taken the
opportunity to lay their eggs there, after finishing the building and
stocking it with provisions. The abandoned property benefited another.
On realizing the usurpation, the Bee returning from her long journey
soon consoled herself for the mishap. She began to break the seals of
some cell or other, adjoining her own; the rest let her have her way,
being doubtless too busy with their present labours to seek a quarrel
with the freebooter. As soon as she had destroyed the lid, the Bee,
with a sort of feverish haste that burned to repay theft by theft, did
a little building, did a little victualling, as though to resume the
thread of her occupations, destroyed the egg in being, laid her own
and closed the cell again. Here was a touch of nature that deserved
careful examination.
At eleven o'clock in the morning, when the work is at its height, I
mark half-a-score of Chalicodomae with different colours, to
distinguish them from one another. Some are occupied with building,
others are disgorging honey. I mark the corresponding cells in the
same way. As soon as the marks are quite dry, I catch the ten Bees,
place them singly in screws of paper and shut them all in a box until
the next morning. After twenty-four hours' captivity, the prisoners
are released. During their absence, their cells have disappeared under
a layer of recent structures; or, if still exposed to view, they are
closed and others have made use of them.
As soon as they are free, the ten Bees, with one exception, return to
their respective tiles. They do more than this, so accurate is their
memory, despite the confusion resulting from a prolonged
incarceration: they return to the cell which they have built, the
beloved stolen cell; they minutely explore the outside of it, or at
least what lies nearest to it, if the cell has disappeared under the
new structures. In cases where the home is not henceforward
inaccessible, it is at least occupied by a strange egg and the door is
securely fastened. To this reverse of fortune the ousted ones retort
with the brutal lex talionis: an egg for an egg, a cell for a cell.
You've stolen my house; I'll steal yours. And, without much
hesitation, they proceed to force the lid of a cell that suits them.
Sometimes they recover possession of their own home, if it is possible
to get into it; sometimes and more frequently they seize upon some one
else's, even at a considerable distance from their original dwelling.
Patiently they gnaw the mortar lid. As the general rough-cast covering
all the cells is not applied until the end of the work, all that they
need do is to demolish the lid, a hard and wearisome task, but not
beyond the strength of their mandibles. They therefore attack the
door, the cement disk, and reduce it to dust. The criminal is allowed
to carry out her nefarious designs without the slightest interference
or protest from any of her neighbours, though these must necessarily
include the chief party interested. The Bee is as forgetful of her
cell of yesterday as she is jealous of her actual cell. To her the
present is everything; the past means nothing; and the future means no
more. And so the population of the tile leave the breakers of doors to
do their business in peace; none hastens to the defence of a home that
might well be her own. How differently things would happen if the cell
were still on the stocks! But it dates back to yesterday, to the day
before; and no one gives it another thought.
It's done: the lid is demolished; access is free. For some time, the
Bee stands bending over the cell, her head half-buried in it, as
though in contemplation. She goes away, she returns undecidedly; at
last she makes up her mind. The egg is snapped up from the surface of
the honey and flung on the rubbish-heap with no more ceremony than if
the Bee were ridding the house of a bit of dirt. I have witnessed this
hideous crime again and yet again; I confess to having repeatedly
provoked it. In housing her egg, the Mason-bee displays a brutal
indifference to the fate of her neighbour's egg.
I see some of them afterwards busy provisioning, disgorging honey and
brushing pollen into the cell already completely provisioned; I see
some masoning a little at the orifice, or at least laying on a few
trowels of mortar. It seems as if the Bee, although the victuals and
the building are just as they should be, were resuming the work at the
point at which she left it twenty-four hours before. Lastly, the egg
is laid and the opening closed up. Of my captives, one, less patient
than the rest, rejects the slow process of eating away the cover and
decides in favour of robbery with violence, on the principle that
might is right. She dislodges the owner of a half-stocked cell, keeps
good watch for a long time on the threshold of the home and, when she
feels herself the mistress of the house, goes on with the
provisioning. I follow the ousted proprietress with my eyes. I see her
seize upon a closed cell by breaking into it, behaving in all respects
like my imprisoned Chalicodomae.
The whole occurrence was too significant to be left without further
confirmation. I repeated the experiment, therefore, almost every year,
always with the same success. I can only add that, among the Bees
placed by my artifices under the necessity of making up for lost time,
a few are of a more easy-going temperament. I see some building anew,
as if nothing out of the way had happened; others--this is a very rare
course--going to settle on another tile, as though to avoid a society
of thieves; and lastly a few who bring pellets of mortar and zealously
finish the lid of their own cell, although it contains a strange egg.
However, housebreaking is the usual thing.
One more detail not without value: it is not necessary for you to
intervene and imprison Mason-bees for a time in order to witness the
acts of violence which I have described. If you follow the work of the
swarm assiduously, you may occasionally find a surprise awaiting you.
A Mason-bee will appear and, for no reason known to you, break open a
door and lay her egg in the violated cell. From what goes before, I
look upon the Bee as a laggard, kept away from the workyard by an
accident, or else carried to a distance by a gust of wind. On
returning after an absence of some duration, she finds her place
taken, her cell used by another. The victim of an usurper's villainy,
like the prisoners in my paper screws, she behaves as they do and
indemnifies herself for her loss by breaking into another's home.
Lastly, it was a matter of learning the behaviour, after their act of
violence, of the Masons who have smashed in a door, brutally expelled
the egg within and replaced it by one of their own laying. When the
lid is repaired to look as good as new and everything restored to
order, will they continue their burglarious ways and exterminate the
eggs of others to make room for their own? By no means. Revenge, that
pleasure of the gods and perhaps also of Bees, is satisfied after one
cell has been ripped open. All anger is appeased when the egg for
which so much work has been done is safely housed. Henceforth, both
prisoners and stray laggards resume their ordinary labours,
indifferently with the rest. They build honestly, they provision
honestly, nor meditate further evil. The past is quite forgotten until
a fresh disaster occurs.
To return to the parasites: a mother chanced to find herself the
mistress of another's nest. She took advantage of this to entrust her
egg to it. This expeditious method, so easy for the mother and so
favourable to the success of her offspring, made such an impression on
her that she transmitted the maternal indolence to her posterity. Thus
the worker gradually became transformed into a parasite.
Capital! The thing goes like clockwork, as long as we have only to put
our ideas on paper. But let us just consult the facts, if you don't
mind; before arguing about probabilities, let us look into things as
they are. Here is the Mason-bee of the Sheds teaching us something
very curious. To smash the lid of a cell that does not belong to her,
to throw the egg out of doors and put her own in its place is a
practice which she has followed since time began. There is no need of
my interference to make her commit burglary: she commits it of her own
accord, when her rights are prejudiced as the result of a too-long
absence. Ever since her race has been kneading cement, she has known
the law of retaliation. Countless ages, such as the evolutionists
require, have made her adopt forcible usurpation as an inveterate
habit. Moreover, robbery is so incomparably easy for the mother. No
more cement to scratch up with her mandibles on the hard ground, no
more mortar to knead, no more clay walls to build, no more pollen to
gather on hundreds and hundreds of journeys. All is ready, board and
lodging. Never was a better opportunity for allowing one's self a good
time. There is nothing against it. The others, the workers, are
imperturbable in their good-humour. Their outraged cells leave them
profoundly indifferent. There are no brawls to fear, no protests. Now
or never is the moment to tread the primrose path.
Besides, your progeny will be all the better for it. You can choose
the warmest and wholesomest spots; you can multiply your laying-
operations by devoting to them all the time that you would have to
spend on irksome occupations. If the impression produced by the
violent seizure of another's property is strong enough to be handed
down by heredity, how deep should be the impression of the actual
moment when the Mason-bee is in the first flush of success! The
precious advantage is fresh in the memory, dating from that very
instant; the mother has but to continue in order to create a method of
installation favourable in the highest degree to her and hers. Come,
poor Bee! Throw aside your exhausting labours, follow the
evolutionists' advice and, as you have the means at your disposal,
become a parasite!
But no, having effected her little revenge, the builder returns to her
masonry, the gleaner to her gleaning, with unquenchable zeal. She
forgets the crime committed in a moment of anger and takes good care
not to hand down any tendency towards idleness to her offspring. She
knows too well that activity is life, that work is the world's great
joy. What myriads of cells has she not broken open since she has been
building; what magnificent opportunities, all so clear and conclusive,
has she not had to emancipate herself from drudgery! Nothing could
convince her: born to work, she persists in an industrious life. She
might at least have produced an offshoot, a race of housebreakers, who
would invade cells by demolishing doors. The Stelis does something of
the kind; but who would think of proclaiming a relationship between
the Chalicodoma and her? The two have nothing in common. I call for a
scion of the Mason-bee of the Sheds who shall live by the art of
breaking through ceilings. Until they show me one, the theorists will
only make me smile when they talk to me of erstwhile workers
relinquishing their trade to become parasitic sluggards.
I also call, with no less insistence, for a descendant of the Three-
horned Osmia, a descendant given to demolishing party-walls. I will
describe later how I managed to make a whole swarm of these Osmiae
build their nests on the table in my study, in glass tubes that
enabled me to see the inmost secrets of the work of the Bee. (Cf.
"Bramble-bees and Others", by J. Henri Fabre, translated by Alexander
Teixeira de Mattos: chapters 1 to 7.--Translator's Note.) For three or
four weeks, each Osmia is scrupulously faithful to her tube, which is
laboriously filled with a set of chambers divided by earthen
partitions. Marks of different colours painted on the thorax of the
workers enable me to recognize individuals in the crowd. Each crystal
gallery is the exclusive property of one Osmia; no other enters it,
builds in it or hoards in it. If, through heedlessness, through
momentary forgetfulness of her own house in the tumult of the city,
some neighbour so much as comes and looks in at the door, the owner
soon puts her to flight. No such indiscretion is tolerated. Every Bee
has her home and every home its Bee.
All goes well until just before the end of the work. The tubes are
then closed at the orifice with a thick plug of earth; nearly the
whole swarm has disappeared; there remain on the spot a score of
tatterdemalions in threadbare fleeces, worn out by a month's hard
toil. These laggards have not finished their laying. There is no lack
of unoccupied tubes, for I take care to remove some of those which are
full and to replace them by others that have not yet been used. Very
few of the Bees decide to take possession of these new homes, which
differ in no particular from the earlier ones; and even then they
build only a small number of cells, which are often mere attempts at
partitions.
They want something different: a nest belonging to some one else. They
bore through the stopper of the inhabited tubes, a work of no great
difficulty, for we have here not the hard cement of the Chalicodoma,
but a simple lid of dried mud. When the entrance is cleared, a cell
appears, with its store of provisions and its egg, with her brutal
mandibles; she rips it open and goes and flings it away. She does
worse: she eats it on the spot. I had to witness this horror many
times over before I could accept it as a fact. Note that the egg
devoured may very well contain the criminal's own offspring.
Imperiously swayed by the needs of her present family, the Osmia puts
her past family entirely out of her mind.
Having perpetrated this child-murder, the depraved creature does a
little provisioning. They all experience the same necessity to go
backwards in the sequence of actions in order to pick up the thread of
their interrupted occupations. Her next work is to lay her egg and
then she conscientiously restores the demolished lid.
The havoc can be more sweeping still. One of these laggards is not
satisfied with a single cell; she needs two, three, four. To reach the
most remote, the Osmia wrecks all those which come before it. The
partitions are broken down, the eggs eaten or thrown away, the
provisions swept outside and often even carried to a distance in great
lumps. Covered with dust from the loose plaster of the demolition,
floured all over with the rifled pollen, sticky with the contents of
the mangled eggs, the Osmia, while at her brigand's work, is altered
beyond recognition. Once the place is cleared, everything resumes its
normal course. Provisions are laboriously brought to take the place of
those which have been thrown away; eggs are laid, one on each heap of
food; the partitions are built up again; and the massive plug sealing
the whole structure is made as good as new.
Crimes of this kind recur so often that I am obliged to interfere and
place in safety the nests which I wish to keep intact. And nothing as
yet explains this brigandage, bursting forth at the end of the work
like a moral epidemic, like a frenzied delirium. I should say nothing
if the site were lacking; but the tubes are there, close by, empty and
quite fit to receive the eggs. The Osmia refuses them, she prefers to
plunder. Is it from weariness, from a distaste for work after a period
of fierce activity? Not at all; for, when a row of cells has been
stripped of its contents, after the ravage and waste, she has to come
back to ordinary work, with all its burdens. The labour is not
reduced; it is increased. It would pay the Bee infinitely better, if
she wants to continue her laying, to make her home in an unoccupied
tube. The Osmia thinks differently. Her reasons for acting as she does
escape me. Can there be ill-conditioned characters among her,
characters that delight in a neighbour's ruin? There are among men.
In the privacy of her native haunts, the Osmia, I have no doubt,
behaves as in my crystal galleries. Towards the end of the building-
operations, she violates others' dwellings. By keeping to the first
cell, which it is not necessary to empty in order to reach the next,
she can utilize the provisions on the spot and shorten to that extent
the longest part of her work. As usurpations of this kind have had
ample time to become inveterate, to become inbred in the race, I ask
for a descendant of the Osmia who eats her grandmother's egg in order
to establish her own egg.
This descendant I shall not be shown; but I may be told that she is in
process of formation. The outrages which I have described are
preparing a future parasite. The transformists dogmatize about the
past and dogmatize about the future, but as seldom as possible talk to
us about the present. Transformations have taken place,
transformations will take place; the pity of it is that they are not
actually taking place. Of the three tenses, one is lacking, the very
one which directly interests us and which alone is clear of the
incubus of theory. This silence about the present does not please me
overmuch, scarcely more than the famous picture of "The Crossing of
the Red Sea" painted for a village chapel. The artist had put upon the
canvas a broad ribbon of brightest scarlet; and that was all.
'Yes, that's the Red Sea,' said the priest, examining the masterpiece
before paying for it. 'That's the Red Sea, right enough; but where are
the Israelites?'
'They have passed,' replied the painter.
'And the Egyptians?'
'They are on the way.'
Transformations have passed, transformations are on the way. For
mercy's sake, cannot they show us transformations in the act? Must the
facts of the past and the facts of the future necessarily exclude the
facts of the present? I fail to understand.
I call for a descendant of the Chalicodoma and a descendant of the
Osmia who have robbed their neighbours with gusto, when occasion
offered, since the origin of their respective races, and who are
working industriously to create a parasite happy in doing nothing.
Have they succeeded? No. Will they succeed? Yes, people maintain. For
the moment, nothing. The Osmiae and Chalicodomae of to-day are what
they were when the first trowel of cement or mud was mixed. Then how
many ages does it take to form a parasite? Too many, I fear, for us
not to be discouraged.
If the sayings of the theorists are well-founded, going on strike and
living by shifts was not always enough to assure parasitism. In
certain cases, the animal must have had to change its diet, to pass
from live prey to vegetarian fare, which would entirely subvert its
most essential characteristics. What should we say to the Wolf giving
up mutton and browsing on grass, in obedience to the dictates of
idleness? The boldest would shrink from such an absurd assumption. And
yet transformism leads us straight to it.
Here is an example: in July, I split some bramble-stems in which Osmia
tridentata has built her nests. In the long series of cells, the lower
already hold the Osmia's cocoons, while the upper contain the larva
which has nearly finished consuming its provisions and the topmost
show the victuals untouched, with the Osmia's egg upon them. It is a
cylindrical egg, rounded at both extremities, of a transparent white
and measuring four to five millimetres in length. (.156 to .195 inch.-
-Translator's Note.) It lies slantwise, one end of it resting on the
food and the other sticking up at some distance above the honey. Now,
by multiplying my visits to the fresh cells, I have on several
occasions made a very valuable discovery. On the free end of the
Osmia's egg, another egg is fixed; an egg quite different in shape,
white and transparent like the first, but much smaller and narrower,
blunt at one end and tapering into a rather sharp point at the other.
It is two millimetres long by half a millimetre wide. (.078 and .019
inch.--Translator's Note.) It is undeniably the egg of a parasite, a
parasite which compels my attention by its curious method of
installing its family.
It opens before the Osmia's egg. The tiny grub, as soon as it is born,
begins to drain the rival egg, of which it occupied the top part, high
up above the honey. The extermination soon becomes perceptible. You
can see the Osmia's egg turning muddy, losing its brilliancy, becoming
limp and wrinkled. In twenty-four hours, it is nothing but an empty
sheath, a crumpled bit of skin. All competition is now removed; the
parasite is the master of the house. The young grub, when demolishing
the egg, was active enough: it explored the dangerous thing which had
to be got rid of quickly, it raised its head to select and multiply
the attacking-points. Now, lying at full length on the surface of the
honey, it no longer shifts its position; but the undulations of the
digestive canal betray its greedy absorption of the Osmia's store of
food. The provisions are finished in a fortnight and the cocoon is
woven. It is a fairly firm ovoid, of a very dark-brown colour, two
characteristics which at once distinguish it from the Osmia's pale,
cylindrical cocoon. The hatching takes place in April or May. The
puzzle is solved at last: the Osmia's parasite is a Wasp called the
Spotted Sapyga (Sapyga punctata, V.L.)
Now where are we to class this Wasp, a true parasite in the strict
sense of the word, that is to say, a consumer of others' provisions.
Her general appearance and her structure make it clear to any eye more
or less familiar with entomological shapes that she belongs to a
species akin to that of the Scoliae. Moreover, the masters of
classification, so scrupulous in their comparison of characteristics,
agree in placing the Sapygae immediately after the Scoliae and a
little before the Mutillae. The Scoliae feed their grubs on prey; so
do the Mutillae. The Osmia's parasite, therefore, if it really derives
from a transformed ancestor, is descended from a flesh-eater, though
it is now an eater of honey. The Wolf does more than become a Sheep:
he turns himself into a sweet-tooth.
'You will never get an apple-tree out of an acorn,' Franklin tells us,
with that homely common-sense of his.
In this case, the passion for jam must have sprung from a love of
venison. Any theory might well be deficient in balance when it leads
to such vagaries as this.
I should have to write a volume if I would go on setting forth my
doubts. I have said enough for the moment. Man, the insatiable
enquirer, hands down from age to age his questions about the whys and
wherefores of origins. Answer follows answer, is proclaimed true
to-day and recognized as false tomorrow; and the goddess Isis
continues veiled.
CHAPTER 10. THE TRIBULATIONS OF THE MASON-BEE.
To illustrate the methods of those who batten on others' goods, the
plunderers who know no rest till they have wrought the destruction of
the worker, it would be difficult to find a better instance than the
tribulations suffered by the Chalicodoma of the Walls. The Mason who
builds on the pebbles may fairly boast of being an industrious
workwoman. Throughout the month of May, we see her black squads, in
the full heat of the sun, digging with busy teeth in the mortar-quarry
of the road hard by. So great is her zeal that she hardly moves out of
the way of the passer-by; more than one allows herself to be crushed
underfoot, absorbed as she is in collecting her cement.
The hardest and driest spots, which still retain the compactness
imparted by the steam-roller, are the favourite veins; and the work of
making the pellet is slow and painful. It is scraped up atom by atom;
and, by means of saliva, turned into mortar then and there. When it is
all well kneaded and there is enough to make a load, the Mason sets
off with an impetuous flight, in a straight line, and makes for her
pebble, a few hundred paces away. The trowel of fresh mortar is soon
spent, either in adding another storey to the turret-shaped edifice,
or in cementing into the wall lumps of gravel that give it greater
solidity. The journeys in search of cement are renewed until the
structure attains the regulation height. Without a moment's rest, the
Bee returns a hundred times to the stone-yard, always to the one spot
recognized as excellent.
The victuals are now collected: honey and flower-dust. If there is a
pink carpet of sainfoin anywhere in the neighbourhood, 'tis there that
the Mason goes plundering by preference, though it cost her a four
hundred yards' journey every time. Her crop swells with honeyed
exudations, her belly is floured with pollen. Back to the cell, which
slowly fills; and back straightway to the harvest-field. And all day
long, with not a sign of weariness, the same activity is maintained as
long as the sun is high enough. When it is late, if the house is not
yet closed, the Bee retires to her cell to spend the night there, head
downwards, tip of her abdomen outside, a habit foreign to the
Chalicodoma of the Sheds. Then and then alone the Mason rests; but it
is a rest that is in a sense equivalent to work, for, thus placed, she
blocks the entrance to the honey-store and defends her treasure
against twilight or night marauders.
Being anxious to form some estimate of the total distance covered by
the Bee in the construction and provisioning of a single cell, I
counted the number of steps from a nest to the road where the mortar
was mixed and from the same nest to the sainfoin-field where the
harvest was gathered. I took such note as my patience permitted of the
journeys made in both directions; and, completing these data with a
comparison between the work done and that which remained to do, I
arrived at nine and a half miles as the result of the total
travelling. Of course, I give this figure only as a rough calculation;
greater precision would have demanded more perseverance than I can
boast.
Such as it is, the result, which is probably under the actual figure
in many cases, is of a kind that gives us a vivid idea of the Mason-
bee's activity. The complete nest will comprise about fifteen cells.
Moreover, the heap of cells will be coated at the end with a layer of
cement a good finger's-breadth thick. This massive fortification,
which is less finished than the rest of the work but more expensive in
materials, represents perhaps in itself one half of the complete task,
so that, to establish her dome, Chalicodoma muraria, coming and going
across the arid table-land, traverses altogether a distance of 275
miles, which is nearly half of the greatest dimension of France from
north to south. Afterwards, when, worn out with all this fatigue, the
Bee retires to a hiding-place to languish in solitude and die, she is
surely entitled to say:
'I have laboured, I have done my duty!'
Yes, certainly, the Mason has toiled with a vengeance. To ensure the
future of her offspring, she has spent her own life without reserve,
her long life of five or six weeks' duration; and now she breathes her
last, contented because everything is in order in the beloved house:
copious rations of the first quality; a shelter against the winter
frosts; ramparts against incursions of the enemy. Everything is in
order, at least so she thinks; but, alas, what a mistake the poor
mother is making! Here the hateful fatality stands revealed, aspera
fata, which ruins the producer to provide a living for the drone; here
we see the stupid and ferocious law that sacrifices the worker for the
idler's benefit. What have we done, we and the insects, to be ground
with sovran indifference under the mill-stone of such wretchedness?
Oh, what terrible, what heart-rending questions the Mason-bee's
misfortunes would bring to my lips, if I gave free scope to my sombre
thoughts! But let us avoid these useless whys and keep within the
province of the mere recorder.
There are some ten of them plotting the ruin of the peaceable and
industrious Bee; and I do not know them all. Each has her own tricks,
her own art of injury, her own exterminating tactics, so that no part
of the Mason's work may escape destruction. Some seize upon the
victuals, others feed on the larvae, others again convert the dwelling
to their own use. Everything has to submit: cell, provisions, scarce-
weaned nurselings.
The stealers of food are the Stelis-wasp (Stelis nasuta) and the
Dioxys-bee (Dioxys cincta). I have already said how, in the Mason's
absence, the Stelis perforates the dome of cell after cell, lays her
eggs there and afterwards repairs the breach with a mortar made of red
earth, which at once betrays the parasite's presence to a watchful
eye. The Stelis, who is much smaller than the Chalicodoma, finds
enough food in a single cell for the rearing of several of her grubs.
The mother lays a number of eggs, which I have seen vary between the
extremes of two and twelve, on the surface, next to the Mason's egg,
which itself undergoes no outrage whatever.
Things do not go so badly at first. The feasters swim--it is the only
word--in the midst of plenty; they eat and digest like brothers.
Presently, times become hard for the hostess' son; the food decreases,
dearth sets in; and at length not an atom remains, although the
Mason's larva has attained at most a quarter of its growth. The
others, more expeditious feeders, have exhausted the victuals long
before the victim has finished his normal repast. The swindled grub
shrivels up and dies, while the gorged larvae of the Stelis begin to
spin their strong little brown cocoons, pressed close together and
lumped into one mass, so as to make the best use of the scanty space
in the crowded dwelling. Should you inspect the cell later, you will
find, between the heaped cocoons on the wall, a little dried-up
corpse. It is the larva that was such an object of care to the mother
Mason. The efforts of the most laborious of lives have ended in this
lamentable relic. It has happened to me just as often, when examining
the secrets of the cell which is at once cradle and tomb, not to come
upon the deceased grub at all. I picture the Stelis, before laying her
own eggs, destroying the Chalicodoma's egg and eating it, as the
Osmiae do among themselves; or I picture the dying thing, an irksome
mass for the numerous spinners at work in a narrow habitation, being
cut to pieces to make room for the medley of cocoons. But to so many
deeds of darkness I would not like to add another by an oversight; and
I prefer to admit that I failed to perceive the grub that died of
hunger.
Let us now show up the Dioxys. At the time when the work of
construction is in progress, she is an impudent visitor of the nests,
exploiting with the same effrontery the enormous cities of the Mason-
bee of the Sheds and the solitary cupolas of the Mason-bee of the
Pebbles. An innumerable population, coming and going, humming and
buzzing, strikes her with no awe. On the tiles hanging from the walls
of my porch I see her, with her red scarf round her body, stalking
with sublime assurance over the ridged expanse of nests. Her black
schemes leave the swarm profoundly indifferent; not one of the workers
dreams of chasing her off, unless she should come bothering too
closely. Even then, all that happens is a few signs of impatience on
the part of the hustled Bee. There is no serious excitement, no eager
pursuits such as the presence of a mortal enemy might lead us to
suspect. They are there in their thousands, each armed with her
dagger; any one of them is capable of slaying the traitress; and not
one attacks her. The danger is not suspected.
Meanwhile, she inspects the workyard, moves freely among the ranks of
the Masons and bides her time. If the owner be absent, I see her
diving into a cell, coming out again a moment later with her mouth
smeared with pollen. She has been to try the provisions. A dainty
connoisseur, she goes from one store to another, taking a mouthful of
honey. Is it a tithe for her personal maintenance, or a sample tested
for the benefit of her coming grub? I should not like to say. What I
do know is that, after a certain number of these tastings, I catch her
stopping in a cell, with her abdomen at the bottom and her head at the
orifice. This is the moment of laying, unless I am much mistaken.
When the parasite is gone, I inspect the home. I see nothing abnormal
on the surface of the mass. The sharper eye of the owner, when she
gets back, sees nothing either, for she continues the victualling
without betraying the least uneasiness. A strange egg, laid on the
provisions, would not escape her. I know how clean she keeps her
warehouse; I know how scrupulously she casts out anything introduced
by my agency: an egg that is not hers, a bit of straw, a grain of
dust. So, according to my evidence and that of the Chalicodoma, which
is more conclusive, the Dioxys's egg, if it is really laid then, is
not placed on the surface.
I suspect, without having yet verified my suspicion--and I reproach
myself for the neglect--I suspect that the egg is buried in the heap
of pollen-dust. When I see the Dioxys come out of a cell with her
mouth all over yellow flour, perhaps she has been surveying the ground
and preparing a hiding-place for her egg. What I take for a mere
tasting might well be a more serious act. Thus concealed, the egg
escapes the eagle eye of the Bee, whereas, if left uncovered, it would
inevitably perish, would be flung on the rubbish heap at once by the
owner of the nest. When the Spotted Sapyga lays her egg on that of the
Bramble-dwelling Osmia, she does the deed under cover of darkness, in
the gloom of a deep well to which not the least ray of light can
penetrate; and the mother, returning with her pellet of green putty to
build the closing partition, does not see the usurping germ and is
ignorant of the danger. But here everything happens in broad daylight;
and this demands more cunning in the method of installation.
Besides, it is the one favourable moment for the Dioxys. If she waits
for the Mason-bee to lay, it is too late, for the parasite is not able
to break down doors, as the Stelis does. As soon as her egg is laid,
the Mason-bee of the Sheds comes out of her cell and at once turns
round and proceeds to close it up with the pellet of mortar which she
holds ready in her mandibles. The material is employed with such
method that the actual sealing is done in a moment: the other pellets,
the object of repeated journeys, will serve merely to increase the
thickness of the lid. The chamber is inaccessible to the Dioxys from
the first touch of the trowel. Hence it is absolutely necessary for
her to see to her egg before the Mason-bee of the Sheds has disposed
of hers and no less necessary to conceal it from the Mason's watchful
eye.
The difficulties are not so great in the nests of the Mason-bee of the
Pebbles. After this Bee has laid her egg, she leaves it for a time to
go in search of the cement needed for closing the cell; or, if she
already holds a pellet in her mandibles, this is not enough to seal it
properly, as the orifice is larger. More pellets are needed to wall up
the entrance entirely. The Dioxys would have time to strike her blow
during the mother's absences; but everything seems to suggest that she
behaves on the pebbles as she does on the tiles. She steals a march by
hiding the egg in the mass of pollen and honey.
What becomes of the Mason's egg confined in the same cell with the egg
of the Dioxys? In vain have I opened nests at every season; I have
never found a vestige of the egg nor of the grub of either
Chalicodoma. The Dioxys, whether as a larva on the honey, or enclosed
in its cocoon, or as the perfect insect, was always alone. The rival
had disappeared without a trace. A suspicion thereupon suggests
itself; and the facts are so compelling that the suspicion is almost
equal to a certainty. The parasitic grub, which hatches earlier than
the other, emerges from its hiding-place, from the midst of the honey,
comes to the surface and, with its first bite, destroys the egg of the
Mason-bee, as the Sapyga does the egg of the Osmia. It is an odious,
but a supremely efficacious method. Nor must we cry out too loudly
against such foul play on the part of a new born infant: we shall meet
with even more heinous tactics later. The criminal records of life are
full of these horrors which we dare not search too deeply. An
infinitesimal creature, a barely-visible grub, with the swaddling-
clothes of its egg still clinging to it, is led by instinct, at its
first inspiration, to exterminate whatever is in its way.
So the Mason's egg is exterminated. Was it really necessary in the
Dioxys' interest? Not in the least. The hoard of provisions is too
large for its requirements in a cell of the Chalicodoma of the Sheds;
how much more so in a cell of the Chalicodoma of the Pebbles! She eats
not a half, hardly a third of it. The rest remains as it was,
untouched. We see here, in the destruction of the Mason's egg, a
flagrant waste which aggravates the crime. Hunger excuses many things;
for lack of food, the survivors on the raft of the Medusa indulged in
a little cannibalism; but here there is enough food and to spare. When
there is more than she needs, what earthly motive impels the Dioxys to
destroy a rival in the germ stage? Why cannot she allow the larva, her
mess-mate, to take advantage of the remains and afterwards to shift
for itself as best it can? But no: the Mason-bee's offspring must
needs be stupidly sacrificed on the top of provisions which will only
grow mouldy and useless! I should be reduced to the gloomy
lucubrations of a Schopenhauer if I once let myself begin on
parasitism.
Such is a brief sketch of the two parasites of the Chalicodoma of the
Pebbles, true parasites, consumers of provisions hoarded on behalf of
others. Their crimes are not the bitterest tribulations of the Mason-
bee. If the first starves the Mason's grub to death, if the second
makes it perish in the egg, there are others who have a more pitiable
ending in store for the worker's family. When the Bee's grub, all
plump and fat and greasy, has finished its provisions and spun its
cocoon wherein to sleep the slumber akin to death, the necessary
period of preparation for its future life, these other enemies hasten
to the nests whose fortifications are powerless against their
hideously ingenious methods. Soon on the sleeper's body lies a nascent
grub which feasts in all security on the luscious fare. The traitors
who attack the larvae in their lethargy are three in number: an
Anthrax, a Leucopsis and a microscopic dagger-wearer. (Monodontomerus
cupreus. For this and the Anthrax, cf. "The Life of the Fly": chapters
2 and 3. The Leucopsis is a Hymenopteron, the essay upon whom forms
the concluding chapter of the present volume.--Translator's Note.)
Their story deserves to be told without reticence; and I shall tell it
later. For the moment, I merely mention the names of the three
exterminators.
The provisions are stolen, the egg is destroyed. The young grub dies
of hunger, the larva is devoured. Is that all? Not yet. The worker
must be exploited thoroughly, in her work as well as in her family.
Here are some now who covet her dwelling. When the Mason is
constructing a new edifice on a pebble, her almost constant presence
is enough to keep the aspirants to free lodgings at a distance; her
strength and vigilance overawe whoso would annex her masonry. If, in
her absence, one greatly daring thinks of visiting the building, the
owner soon appears upon the scene and ousts her with the most
discouraging animosity. She has no need then to fear the entrance of
unwelcome tenants while the house is new. But the Bee of the Pebbles
also uses old dwellings for her laying, as long as they are not too
much dilapidated. In the early stages of the work, neighbours compete
for these with an eagerness which shows the value attached to them.
Face to face, at times with their mandibles interlocked, now both
rising into the air, now coming down again, then touching ground and
rolling over each other, next flying up again, for hours on end they
will wage battle for the property at issue.
A ready-made nest, a family heirloom which needs but a little
restoring, is a precious thing for the Mason, ever sparing of her
time. We find so many of the old homes repaired and restocked that I
suspect the Bee of laying new foundations only when there are no
secondhand nests to be had. To have the chambers of a dome occupied by
a stranger therefore means a serious privation.
Now several Bees, however industrious in gathering honey, building
party-walls and contriving receptacles for provisions, are less clever
at preparing the resorts in which the cells are to be stacked. The
abandoned chambers of the Chalicodoma, now larger than they were
originally, through the addition of the hall of exit, are first-rate
acquisitions for them. The great thing is to occupy these chambers
first, for here possession is nine parts of the law. Once established,
the Mason is not disturbed in her home, while she, in her turn, does
not disturb the stranger who has settled down before her in an old
nest, the patrimony of her family. The disinherited one leaves the
Bohemian to enjoy the ruined manor in peace and goes to another pebble
to establish herself at fresh expense.
In the first rank of these free tenants, I will place an Osmia (Osmia
cyanoxantha, PEREZ) and a Megachile, or Leaf-cutting Bee (Megachile
apicalis, SPIN.) (Cf. "Bramble-dwellers and Others": chapter 8.--
Translator's Note.), both of whom work in May, at the same time as the
Mason, while both are small enough to lodge from five to eight cells
in a single chamber of the Chalicodoma, a chamber increased by the
addition of an outer hall. The Osmia subdivides this space into very
irregular compartments by means of slanting, upright or curved
partitions, subject to the dictates of space. There is no art,
consequently, in the accumulation of little cells; the architect's
only task is to use the breadth at her disposal in a frugal manner.
The material employed for the partitions is a green, vegetable putty,
which the Osmia must obtain by chewing the shredded leaves of a plant
whose nature is still uncertain. The same green paste serves for the
thick plug that closes the abode. But in this case the insect does not
use it unadulterated. To give greater power of resistance to the work,
it mixes a number of bits of gravel with the vegetable cement. These
materials, which are easily picked up, are lavishly employed, as
though the mother feared lest she should not fortify sufficiently the
entrance to her dwelling. They form a sort of coarse stucco, on the
more or less smooth cupola of the Chalicodoma; and this unevenness, as
well as the green colouring of its mortar of masticated leaves, at
once betrays the Osmia's nest. In course of time, under the prolonged
action of the air, the vegetable putty turns brown and assumes a dead-
leaf tint, especially on the outside of the plug; and it would then be
difficult for any one who had not seen them when freshly made to
recognize their nature.
The old nests on the pebbles seem to suit other Osmiae. My notes
mention Osmia Morawitzi, PEREZ, and Osmia cyanea, KIRB., as having
been recognized in these dwellings, although they are not very
assiduous visitors. Lastly, to complete the enumeration of the Bees
known to me as making their homes in the Mason's cupolas, I must add
Megachile apicalis, who piles in each cell a half-dozen or more honey-
pots constructed with disks cut from the leaves of the wild rose, and
an Anthidium whose species I cannot state, having seen nothing of her
but her white cotton sacks.
The Mason-bee of the Sheds, on the other hand, supplies free lodgings
to two species of Osmiae, Osmia tricornis, LATR., and Osmia
Latreillii, SPIN., both of whom are quite common. The Three-horned
Osmia frequents by preference the habitations of the Bees that build
their nests in populous colonies, such as the Chalicodoma of the Sheds
and the Hairy-footed Anthophora. Latreille's Osmia is nearly always
found with the Three-horned Osmia at the Chalicodoma's.
The real builder of the city and the exploiter of the labour of others
work together, at the same period, form a common swarm and live in
perfect harmony, each Bee of the two species attending to her business
in peace. They share and share alike, as though by tacit agreement. Is
the Osmia discreet enough not to put upon the good-natured Mason and
to utilize only abandoned passages and waste cells? Or does she take
possession of the home of which the real owners could themselves have
made use? I lean in favour of usurpation, for it is not rare to see
the Chalicodoma of the Sheds clearing out old cells and using them as
does her sister of the Pebbles. Be this as it may, all this little
busy world lives without strife, some building anew, others dividing
up the old dwelling.
Those Osmiae, on the contrary, who are the self-invited guests of the
Mason-bee of the Pebbles are the sole occupants of the dome. The cause
of this isolation lies in the unsociable temper of the proprietress.
The old nest does not suit her from the moment that she sees it
occupied by another. Instead of going shares, she prefers to seek
elsewhere a dwelling where she can work in solitude. Her gracious
surrender of a most excellent lodging in favour of a stranger who
would be incapable of offering the least resistance if a dispute arose
proves the great immunity enjoyed by the Osmia in the home of the
worker whom she exploits. The common and peaceful swarming of the
Mason-bee of the Sheds and the two cell-borrowing Osmiae proves it in
a still more positive fashion. There is never a fight for the
acquisition of another's goods or the defence of one's own property;
never a brawl between Osmiae and Chalicodomae. Robber and robbed live
on the most neighbourly terms. The Osmia considers herself at home;
and the other does nothing to undeceive her. If the parasites, so
deadly to the workers, move about in their very ranks with impunity,
without arousing the faintest excitement, an equally complete
indifference must be shown by the dispossessed owners to the presence
of the usurpers in their old homes. I should be greatly put to it if I
were asked to reconcile this calmness on the part of the expropriated
one with the ruthless competition that is said to sway the world.
Fashioned so as to instal herself in the Mason's property, the Osmia
meets with a peaceful reception from her. My feeble eyes can see no
further.
I have named the provision-thieves, the grub-murderers and the house-
grabbers who levy tribute on the Mason-bee. Does that end the list?
Not at all. The old nests are cities of the dead. They contain Bees
who, on achieving the perfect state, were unable to open the exit-door
through the cement and who withered in their cells; they contain dead
larvae, turned into black, brittle cylinders; untouched provisions,
both mouldy and fresh, on which the egg has come to grief; tattered
cocoons; shreds of skins; relics of the transformation.
If we remove the nest of the Chalicodoma of the Sheds from its tile--a
nest sometimes quite eight inches thick--we find live inhabitants only
in a thin outer layer. All the remainder, the catacombs of past
generations, is but a horrible heap of dead, shrivelled, ruined,
decomposed things. Into this sub-stratum of the ancient city the
unreleased Bees, the untransformed larvae fall as dust; here the
honey-stores of old go sour, here the uneaten provisions are reduced
to mould.
Three undertakers, all members of the Beetle tribe, a Clerus, a Ptinus
and an Anthrenus, batten on these remains. The larvae of the Anthrenus
and the Ptinus gnaw the ashes of the corpses; the larva of the Clerus,
with the black head and the rest of its body a pretty pink, appeared
to me to be breaking into the old jam-pots filled with rancid honey.
The perfect insect itself, garbed in vermilion with blue ornaments, is
fairly common on the surface of the clay slabs during the working
season, strolling leisurely through the yard to taste here and there
the drops of honey oozing from some cracked pot. Notwithstanding his
showy livery, so unlike the workers' sombre frieze, the Chalicodomae
leave him in peace, as though they recognized in him the scavenger
whose duty it is to keep the sewers wholesome.
Ravaged by the passing years, the Mason's home at last falls into ruin
and becomes a hovel. Exposed as it is to the direct action of wind and
weather, the dome built upon a pebble chips and cracks. To repair it
would be too irksome, nor would that restore the original solidity of
the shaky foundation. Better protected by the covering of a roof, the
city of the sheds resists longer, without however escaping eventual
decay. The storeys which each generation adds to those in which it was
born increase the thickness and the weight of the edifice in alarming
proportions. The moisture of the tile filters into the oldest layers,
wrecks the foundations and threatens the nest with a speedy fall. It
is time to abandon for good the house with its cracks and rents.
Thereupon the crumbling apartments, on the pebble as well as on the
tile, become the home of a camp of gypsies who are not particular
where they find a shelter. The shapeless hovel, reduced to a fragment
of a wall, finds occupants, for the Mason's work must be exploited to
the utmost limits of possibility. In the blind alleys, all that
remains of the former cells, Spiders weave a white-satin screen,
behind which they lie in wait for the passing game. In nooks which
they repair in summary fashion with earthen embankments or clay
partitions, Hunting Wasps--Pompili and Tripoxyla--store up small
members of the Spider tribe, including sometimes the Weaving Spiders
who live in the same ruins.
I have said nothing yet of the Chalicodoma of the Shrubs. My silence
is not due to negligence, but to the circumstance that I am almost
destitute of facts relating to her parasites. Of the many nests which
I have opened in order to study their inhabitants, only one so far has
been invaded by strangers. This nest, the size of a large walnut, was
fixed on a pomegranate-branch. It comprised eight cells, of which
seven were occupied by the Chalicodoma, and the eighth by a little
Chalcis, the plague of a whole host of the Bee-tribe. Apart from this
instance, which was not a very serious case, I have seen nothing. In
those aerial nests, swinging at the end of a twig, not a Dioxys, a
Stelis, an Anthrax, a Leucopsis, those dread ravagers of the other two
Masons; never any Osmiae, Megachiles or Anthidia, those lodgers in the
old buildings.
The absence of the latter is easily explained. The Chalicodoma's
masonry does not last long on its frail support. The winter winds,
when the shelter of the foliage has disappeared, must easily break the
twig, which is little thicker than a straw and liable to give way by
reason of its heavy burden. Threatened with an early fall, if it is
not already on the ground, last year's dwelling is not restored to
serve the needs of the present generation. The same nest does not
serve twice; and this does away with the Osmiae and with their rivals
in the art of utilizing old cells.
The elucidation of this point does not remove the obscurity of the
next. I can see nothing to account for the absence or at least the
extreme rareness of usurpers of provisions and consumers of grubs,
both of whom are very indifferent to the new or old conditions of the
nest, so long as the cells are well stocked. Can it be that the lofty
position of the edifice and the shaky support of the twig arouse
distrust in the Dioxys and other malefactors? For lack of a better
explanation, I will leave it at that.
If my idea is not an empty fancy, we must admit that the Chalicodoma
of the Shrubs was singularly well-inspired in building in mid-air. You
have seen of what misfortunes the other two are victims. If I take a
census of the population of a tile, many a time I find the Dioxys and
the Mason-bee in almost equal proportions. The parasite has wiped out
half the colony. To complete the disaster, it is not unusual for the
grub-eaters, the Leucopsis and her rival, the pygmy Chalcis, to have
decimated the other half. I say nothing of Anthrax sinuata, whom I
sometimes see coming from the nests of the Chalicodoma of the Sheds;
her larva preys on the Three-horned Osmia, the Mason-bee's visitor.
All solitary though she be on her boulder, which would seem the proper
thing to keep away exploiters, the scourge of dense populations, the
Chalicodoma of the Pebbles is no less sorely tried. My notes abound in
cases such as the following: of the nine cells in one dome, three are
occupied by the Anthrax, two by the Leucopsis, two by the Stelis, one
by the Chalcis and the ninth by the Mason. It is as though the four
miscreants had joined forces for the massacre: the whole of the Bee's
family has disappeared, all but one young mother saved from the
disaster by her position in the centre of the citadel. I have
sometimes stuffed my pockets with nests removed from their pebbles
without finding a single one that has not been violated by one or
other of the malefactors and oftener still by several of them at a
time. It is almost an event for me to find a nest intact. After these
funereal records, I am haunted by a gloomy thought: the weal of one
means the woe of another.
CHAPTER 11. THE LEUCOPSES.
(This chapter should be read in conjunction with the essays entitled
"The Anthrax" and "Larval Dimorphism", forming chapters 2 and 4 of
"The Life of the Fly."--Translator's Note.)
Let us visit the nests of Chalicodoma muraria in July, detaching them
from their pebbles with a sideward blow, as I explained when telling
the story of the Anthrax. The Mason-bee's cocoons with two
inhabitants, one devouring, the other in process of being devoured,
are numerous enough to allow me to gather some dozens in the course of
a morning, before the sun becomes unbearably hot. We will give a smart
tap to the flints so as to loosen the clay domes, wrap these up in
newspapers, fill our box and go home as fast as we can, for the air
will soon be as fiery as the devil's kitchen.
Inspection, which is easier in the shade indoors, soon tells us that,
though the devoured is always the wretched Mason-bee, the devourer
belongs to two different species. In the one case, the cylindrical
form, the creamy-white colouring and the little nipple constituting
the head reveal to us the larva of the Anthrax, which does not concern
us at present; in the other, the general structure and appearance
betray the grub of some Hymenopteron. The Mason's second exterminator
is, in fact, a Leucopsis (Leucopsis gigas, FAB.), a magnificent
insect, stripped black and yellow, with an abdomen rounded at the end
and hollowed out, as is also the back, into a groove to contain a long
rapier, as slender as a horsehair, which the creature unsheathes and
drives through the mortar right into the cell where it proposes to
establish its egg. Before occupying ourselves with its capacities as
an inoculator, let us learn how its larva lives in the invaded cell.
It is a hairless, legless, sightless grub, easily confused, by
inexperienced eyes, with those of various honey-gathering Hymenoptera.
Its more apparent characteristics consist of a colouring like that of
rancid butter, a shiny and as it were oily skin and a segmentation
accentuated by a series of marked swellings, so that, when looked at
from the side, the back is very plainly indented. When at rest, the
larva is like a bow bending round at one point. It is made up of
thirteen segments, including the head. This head, which is very small
compared with the rest of the body, displays no mouth-part under the
lens; at most you see a faint red streak, which calls for the
microscope. You then distinguish two delicate mandibles, very short
and fashioned into a sharp point. A small round mouth, with a fine
piercer on the right and left, is all that the powerful instrument
reveals. As for my best single magnifying-glasses, they show me
nothing at all. On the other hand, we can quite easily, without arming
the eye with a lens, perceive the mouth-apparatus--and particularly
the mandibles--of either a honey-eater, such as an Osmia, Chalicodoma
or Megachile, or a game-eater, such as a Scolia, Ammophila or Bembex.
All these possess stout pincers, capable of gripping, grinding and
tearing. Then what is the purpose of the Leucopsis' invisible
implements? His method of consuming will tell us.
Like his prototype, the Anthrax, the Leucopsis does not eat the
Chalicodoma-grub, that is to say, he does not break it up into
mouthfuls; he drains it without opening it and digging into its
vitals. In him again we see exemplified that marvellous art which
consists in feeding on the victim without killing it until the meal is
over, so as always to have a portion of fresh meat. With its mouth
assiduously applied to the unhappy creature's skin, the lethal grub
fills itself and waxes fat, while the fostering larva collapses and
shrivels, retaining just enough life, however, to resist
decomposition. All that remains of the decanted corpse is the skin,
which, when softened in water and blown out, swells into a balloon
without the least escape of gas, thus proving the continuity of the
integument. All the same, the apparently unpunctured bladder has lost
its contents. It is a repetition of what the Anthrax has shown us,
with this difference, that the Leucopsis seems not so well skilled in
the delicate work of absorbing the victim. Instead of the clean white
granule which is the sole residue when the Fly has finished her joint,
the insect with the long probe has a plateful of leavings, not seldom
soiled with the brownish tinge of food that has gone bad. It would
seem that, towards the end, the act of consumption becomes more savage
and does not disdain dead meat. I also notice that the Leucopsis is
not able to get up from dinner or to sit down to it again as readily
as the Anthrax. I have sometimes to tease him with the point of a
hair-pencil in order to make him let go; and, once he has left the
joint, he hesitates a little before putting his mouth to it again. His
adhesion is not the mere result of a kiss like that of a cupping-
glass; it can only be explained by hooks that need releasing.
I now see the use of the microscopic mandibles. Those two delicate
spikes are incapable of chewing anything, but they may very well serve
to pierce the epidermis with an aperture smaller than that made by the
finest needle; and it is through this puncture that the Leucopsis
sucks the juices of his prey. They are instruments made to perforate
the bag of fat which slowly, without suffering any internal injury, is
emptied through an opening repeated here and there. The Anthrax'
cupping-glass is here replaced by piercers of exceeding sharpness and
so short that they cannot hurt anything beyond the skin. Thus do we
see in operation, with a different sort of implements, that wise
system which keeps the provisions fresh for the consumer.
It is hardly necessary to say, to those who have read the story of the
Anthrax, that this kind of feeding would be impossible with a victim
whose tissues possessed their final hardness. The Mason-bee's grub is
therefore emptied by the Leucopsis' larva while it is in a semifluid
state and deep in the torpor of the nymphosis. The last fortnight in
July and the first fortnight in August are the best times to witness
the repast, which I have seen going on for twelve and fourteen days.
Later, we find nothing in the Mason-bee's cocoon except the Leucopsis'
larva, gloriously fat, and, by its side, a sort of thin, rancid
rasher, the remains of the deceased wet-nurse. Things then remain as
they are until the hot part of the following summer or at least until
the end of June.
Then appears the nymph, which teaches us nothing striking; and at last
the perfect insect, whose hatching may be delayed until August. Its
exit from the Mason's fortress has no likeness to the strange method
employed by the Anthrax. Endowed with stout mandibles, the perfect
insect splits the ceiling of its abode by itself without much
difficulty. At the time of its deliverance, the Mason-bees, who work
in May, have long disappeared. The nests on the pebbles are all
closed, the provisioning is finished, the larvae are sleeping in their
yellow cocoons. As the old nests are utilized by the Mason so long as
they are not too much dilapidated, the dome which has just been
vacated by the Leucopsis, now more than a year old, has its other
cells occupied by the Bee's children. There is here, without seeking
farther, a fat living for the Leucopsis' offspring which she well
knows how to turn to profit. It depends but on herself to make the
house in which she was born into the residence of her family. Besides,
if she has a fancy for distant exploration, clay domes abound in the
harmas. The inoculation of the eggs through the walls will begin
shortly. Before witnessing this curious performance, let us examine
the needle that is to effect it.
The insect's abdomen is hollowed, at the top, into a furrow that runs
up to the base of the thorax; the end, which is broader and rounded,
has a narrow slit, which seems to divide this region into two. The
whole thing suggests a pulley with a fine groove. When at rest, the
inoculating-needle or ovipositor remains packed in the slit and the
furrow. The delicate instrument thus almost completely encircles the
abdomen. Underneath, on the median line, we see a long, dark-brown
scale, pointed, keel-shaped, fixed by its base to the first abdominal
segment, with its sides prolonged into membranous wings which are
fastened tightly to the insect's flanks. Its function is to protect
the underlying region, a soft-walled region in which the probe has its
source. It is a cuirass, a lid which protects the delicate motor-
machinery during periods of inactivity but swings from back to front
and lifts when the implement has to be unsheathed and used.
We will now remove this lid with the scissors, so as to have the whole
apparatus before our eyes, and then raise the ovipositor with the
point of a needle. The part that runs along the back comes loose
without the slightest difficulty, but the part embedded in the groove
at the end of the abdomen offers a resistance that warns us of a
complication which we did not notice at first. The tool, in fact,
consists of three pieces, a central piece, or inoculating-filament,
and two side-pieces, which together constitute a scabbard. The two
latter are more substantial, are hollowed out like the sides of a
groove and, when uniting, form a complete groove in which the filament
is sheathed. This bivalvular scabbard adheres loosely to the dorsal
part; but, farther on, at the tip of the abdomen and under the belly,
it can no longer be detached, as its valves are welded to the
abdominal wall. Here, therefore, we find, between the two joined
protecting parts, a simple trench in which the filament lies covered
up. As for this filament, it is easily extracted from its sheath and
released down to its base, under the shield formed by the scale.
Seen under the magnifying-glass, it is a round, stiff, horny thread,
midway in thickness between a human hair and a horse-hair. Its tip is
a little rough, pointed and bevelled to some length down. The
microscope becomes necessary if we would see its real structure, which
is much less simple than it at first appears. We perceive that the
bevelled end-part consists of a series of truncated cones, fitting one
into the other, with their wide base slightly projecting. This
arrangement produces a sort of file, a sort of rasp with very much
blunted teeth. When pressed on the slide, the thread divides into four
pieces of unequal length. The two longer end in the toothed bevel.
They come together in a very narrow groove, which receives the two
other, rather shorter pieces. These both end in a point, which,
however, is not toothed and does not project as far as the final rasp.
They also unite to form a groove, which fits into the groove of the
other two, the whole constituting a complete channel or duct.
Moreover, the two shorter pieces, considered together, can move,
lengthwise, in the groove that receives them; they can also move one
over the other, always lengthwise, so much so that, on the slide of
the microscope, their terminal points are seldom situated on the same
level.
If with our scissors we cut a piece of the inoculating-thread from the
living insect and examine the section under the magnifying-glass, we
shall see the inner groove lengthen out and project beyond the outer
groove and then go in again in turn, while from the wound there oozes
a tiny albimunous drop, doubtless proceeding from the liquid that
gives the egg the singular appendage to which we shall come presently.
By means of these longitudinal movements of the inner trench inside
the outer trench and of the sliding, one over the other, of the two
portions of the former, the egg can be despatched to the end of the
ovipositor notwithstanding the absence of any muscular contraction,
which is impossible in a horny conduit.
We have only to press the upper surface of the abdomen to see it
disjoint itself from the first segment, as though the insect had been
cut almost in two at that point. A wide gap or hiatus appears between
the first and second rings; and, under a thin membrane, the base of
the ovipositor bulges out, bent back into a stout hook. Here the
filament passes through the insect from end to end and emerges
underneath. Its issue is therefore near the base of the abdomen,
instead of at the tip, as usual. This curious arrangement has the
effect of shortening the lever-arm of the ovipositor and bringing the
starting-point of the filament nearer to the fulcrum, namely, the legs
of the insect, and of thus assisting the difficult task of inoculation
by making the most of the effort expended.
To sum up, the ovipositor when at rest goes round the abdomen.
Starting at the base, on the lower surface, it runs round the belly
from front to back and then returns from back to front on the upper
surface, where it ends at almost the same level as its starting-point.
Its length is 14 millimetres. (.546 inch--Translator's Note.) This
fixes the limit of the depth which the probe is able to reach in the
Mason-bee's nests.
One last word on the Leucopsis' weapon. In the dying insect, beheaded,
stripped of legs and wings, with a pin stuck through its body, the
sides of the fissure containing the inoculating-thread quiver
violently, as if the belly were going to open, divide in two along the
median line and then reunite its two halves. The thread itself gives
convulsive tremblings; it comes out of its scabbard, goes back and
slips out again. It is as though the laying-implement could not
persuade itself to die before accomplishing its mission. The insect's
supreme aim is the egg; and, so long as the least spark of life
remains, it makes dying efforts to lay.
Leucopsis gigas exploits the nests of the Mason-bee of the Pebbles and
the Mason-bee of the Sheds with equal zest. To observe the insertion
of the egg at my ease and to watch the operator at work over and over
again, I gave the preference to the last-named Mason, whose nests,
removed from the neighbouring roofs by my orders, have hung for some
years in the arch of my basement. These clay hives fastened to tiles
supply me with fresh records each summer. I am much indebted to them
in the matter of the Leucopsis' life-history.
By way of comparison with what took place under my roof, I used to
observe the same scenes on the pebbles of the surrounding wastelands.
My excursions, alas, did not all reward my zeal, which zeal was not
without merit in the merciless sunshine; but still, at rare intervals,
I succeeded in seeing some Leucopsis digging her probe into the mortar
dome. Lying flat on the ground, from the beginning to the end of the
operation, which sometimes lasted for hours, I closely watched the
insect in its every movement, while my Dog, weary of being out of
doors in that scorching heat, would discreetly retire from the fray
and, with his tail between his legs and his tongue hanging out, go
home and stretch himself at full length on the cool tiles of the hall.
How wise he was to scorn this pebble-gazing! I would come in half-
roasted, as brown as a berry, to find my friend Bull wedged into a
corner, his back to the wall, sprawling on all fours, while, with
heaving sides, he panted forth the last sprays of steam from his
overheated interior. Yes, he was much better-advised to return as fast
as he could to the shade of the house. Why does man want to know
things? Why is he not indifferent to them, with the lofty philosophy
of the animals? What interest can anything have for us that does not
fill our stomachs? What is the use of learning? What is the use of
truth, when profit is all that matters? Why am I--the descendant, so
they tell me, of some tertiary Baboon--afflicted with the passion for
knowledge from which Bull, my friend and companion, is exempt?
Why...oh, where have I got to? I was going in, wasn't I, with a
splitting headache? Quick, let us get back to our subject!
It was in the first week of July that I saw the inoculation begin on
my Chalicodoma sicula nests. The parasite is at her task in the
hottest part of the day, close on three o'clock in the afternoon; and
work goes on almost to the end of the month, decreasing gradually in
activity. I count as many as twelve Leucopses at a time on the most
thickly-populated pair of tiles. The insect slowly and awkwardly
explores the nests. It feels the surface with its antennae, which are
bent at a right angle after the first joint. Then, motionless, with
lowered head, it seems to meditate and to debate within itself on the
fitness of the spot. Is it here or somewhere else that the coveted
larva lies? There is nothing outside, absolutely nothing, to tell us.
It is a stony expanse, bumpy but yet very uniform in appearance, for
the cells have disappeared under a layer of plaster, a work of public
interest to which the whole swarm devotes its last days. If I myself,
with my long experience, had to decide upon the suitable point, even
if I were at liberty to make use of a lens for examining the mortar
grain by grain and to auscultate the surface in order to gather
information from the sound emitted, I should decline the job,
persuaded in advance that I should fail nine times out of ten and only
succeed by chance.
Where my discernment, aided by reason and my optical contrivances,
fails, the insect, guided by the wands of its antennae, never
blunders. Its choice is made. See it unsheathing its long instrument.
The probe points normally towards the surface and occupies nearly the
central spot between the two middle-legs. A wide dislocation appears
on the back, between the first and second segments of the abdomen; and
the base of the instrument swells like a bladder through this opening;
while the point strives to penetrate the hard clay. The amount of
energy expended is shown by the way in which the bladder quivers. At
every moment we expect to see the frail membrane burst with the
violence of the effort. But it does not give way; and the wire goes
deeper and deeper.
Raising itself high on its legs, to give free play to its apparatus,
the insect remains motionless, the only sign of its arduous labours
being a slight vibration. I see some perforators who have finished
operating in a quarter of an hour. These are the quickest at the
business. They have been lucky enough to come across a wall which is
less thick and less hard than usual. I see others who spend as many as
three hours on a single operation, three long hours of patient
watching for me, in my anxiety to follow the whole performance to the
end, three long hours of immobility for the insect, which is even more
anxious to make sure of board and lodging for its egg. But then is it
not a task of the utmost difficulty to introduce a hair into the
thickness of a stone? To us, with all the dexterity of our fingers, it
would be impossible; to the insect, which simply pushes with its
belly, it is just hard work.
Notwithstanding the resistance of the substance traversed, the
Leucopsis perseveres, certain of succeeding; and she does succeed,
although I am still unable to understand her success. The material
through which the probe has to penetrate is not a porous substance; it
is homogeneous and compact, like our hardened cement. In vain do I
direct my attention to the exact point where the instrument is at
work; I see no fissure, no opening that can facilitate access. A
miner's drill penetrates the rock only by pulverizing it. This method
is not admissible here; the extreme delicacy of the implement is
opposed to it. The frail stem requires, so it seems to me, a ready-
made way, a crevice through which it can slip; but this crevice I have
never been able to discover. What about a dissolving fluid which would
soften the mortar under the point of the ovipositor? No, for I see not
a trace of humidity around the point where the thread is at work. I
fall back upon a fissure, a lack of continuity somewhere, although my
examination fails to discover any on the Mason-bee's nest. I was
better served in another case. Leucopsis dorsigera, FAB., settles her
eggs on the larva of the Diadem Anthidium, who sometimes makes her
nest in reed-stumps. I have repeatedly seen her insert her auger
through a slight rupture in the side of the reed. As the wall was
different, wood in the latter case and mortar in the former, perhaps
it will be best to look upon the matter as a mystery.
My sedulous attendance, during the best part of July, in front of the
tiles hanging from the walls of the arch, allowed me to reckon the
inoculations. Each time that the insect, on finishing the operation,
removed its probe, I marked in pencil the exact point at which the
instrument was withdrawn; and I wrote down the date beside it. This
information was to be utilized when the Leucopsis finished her
labours.
When the perforators are gone, I proceed with my examination of the
nests, covered with my hieroglyphics, the pencilled notes. One result,
one which I fully expected, compensates me straightway for all my
weary waitings. Under each spot marked in black, under each spot
whence I saw the ovipositor withdrawn, I always find a cell, with not
a single exception. And yet there are intervals of solid stone between
the cells: the partition-walls alone would account for some. Moreover,
the compartments, which are very irregularly disposed by a swarm of
toilers who all work in their own sweet way, have great irregular
cavities between them, which end by being filled up with the general
plastering of the nest. The result of this arrangement is that the
massive portions cover almost the same space as the hollow portions.
There is nothing outside to show whether the underlying regions are
full or empty. It is quite impossible for me to decide if, by digging
straight down, I shall come to a hollow cell or to a solid wall.
But the insect makes no mistake: the excavations under my pencil-marks
bear witness to that; it always directs its apparatus towards the
hollow of a cell. How is it apprised whether the part below is empty
or full? Its organs of information are undoubtedly the antennae, which
feel the ground. They are two fingers of unparalleled delicacy, which
pry into the basement by tapping on the part above it. Then what do
those puzzling organs perceive? A smell? Not at all; I always had my
doubts of that and now I am certain of the contrary, after what I
shall describe in a moment. Do they perceive a sound? Are we to treat
them as a superior kind of microphone, capable of collecting the
infinitesimal echoes of what is full and the reverberations of what is
empty? It is an attractive idea, but unfortunately the antennae play
their part equally well on a host of occasions when there are no
vaults to reverberate. We know nothing and are perhaps destined never
to know anything of the real value of the antennal sense, to which we
have nothing analogous; but, though it is impossible for us to say
what it does perceive, we are at least able to recognize to some
extent what it does not perceive and, in particular, to deny it the
faculty of smell.
As a matter of fact, I notice, with extreme surprise, that the great
majority of the cells visited by the Leucopsis' probe do not contain
the one thing which the insect is seeking, namely, the young larva of
the Mason-bee enclosed in its cocoon. Their contents consist of the
refuse so often met with in old Chalicodoma-nests: liquid honey left
unemployed, because the egg has perished; spoilt provisions, sometimes
mildewed, or sometimes a tarry mass; a dead larva, stiffened into a
brown cylinder; the shrivelled corpse of a perfect insect, which
lacked the strength to effect its deliverance; dust and rubbish which
has come from the exit-window afterwards closed up by the outer
coating of plaster. The odoriferous effluvia that can emanate from
these relics certainly possess very diverse characters. A sense of
smell with any subtlety at all would not be deceived by this stuff,
sour, 'high,' musty or tarry as the case may be; each compartment,
according to its contents, has a special aroma, which we might or
might not be able to perceive; and this aroma most certainly bears no
resemblance to that which we may assume the much-desired fresh larva
to possess. If nevertheless the Leucopsis does not distinguish between
these various cells and drives the probe into all of them
indifferently, is this not an evident proof that smell is no guide
whatever to her in her search? Other considerations, when I was
treating of the Hairy Ammophila, enabled me to assert that the
antennae have no olfactory powers. To-day, the frequent mistakes of
the Leucopsis, whose antennae are nevertheless constantly exploring
the surface, make this conclusion absolutely certain.
The perforator of clay nests has, so it seems to me, delivered us from
an old physiological fallacy. She would deserve studying, if for no
other result than this; but her interest is far from being exhausted.
Let us look at her from another point of view, whose full importance
will not be apparent until the end; let us speak of something which I
was very far from suspecting when I was so assiduously watching the
nests of my Mason-bees.
The same cell can receive the Leucopsis' probe a number of times, at
intervals of several days. I have said how I used to mark in black the
exact place at which the laying-implement had entered and how I wrote
the date of the operation beside it. Well, at many of these already
visited spots, concerning which I possessed the most authentic
documents, I saw the insect return a second, a third and even a fourth
time, either on the same day or some while after, and drive its
inoculating-thread in again, at precisely the same place, as though
nothing had happened. Was it the same individual repeating her
operation in a cell which she had visited before but forgotten, or
different individuals coming one after the other to lay an egg in a
compartment thought to be unoccupied? I cannot say, having neglected
to mark the operators, for fear of disturbing them.
As there is nothing, except the mark of my pencil, a mark devoid of
meaning to the insect, to indicate that the auger has already been at
work there, it may easily happen that the same operator, finding under
her feet a spot already exploited by herself but effaced from her
memory, repeats the thrust of her tool in a compartment which she
believes herself to be discovering for the first time. However
retentive its memory for places may be, we cannot admit that the
insect remembers for weeks on end, as well as point by point, the
topography of a nest covering a surface of some square yards. Its
recollections, if it have any, serve it badly; the outward appearance
gives it no information; and its drill enters wherever it may happen
to discover a cell, at points that have already perhaps been pierced
several times over.
It may also happen--and this appears to me the most frequent case--
that one exploiter of a cell is succeeded by a second, a third, a
fourth and others still, all fired with the newcomer's zeal because
their predecessors have left no trace of their passage. In one way or
another, the same cell is exposed to manifold layings, though its
contents, the Chalicodoma-grub, be only the bare ration of a single
Leucopsis-grub.
These reiterated borings are not at all rare: I noted a score of them
on my tiles; and, in the case of some cells, the operation was
repeated before my eyes as often as four times. Nothing tells us that
this number was not exceeded in my absence. The little that I observed
prevents me from fixing any limit. And now a momentous question
arises: is the egg really laid each time that the probe enters a cell?
I can see not the slightest excuse for supposing the contrary. The
ovipositor, because of its horny nature, can have but a very dull
sense of touch. The insect is apprised of the contents of the cell
only by the end of that long horse-hair, a not very trustworthy
witness, I should imagine. The absence of resistance tells it that it
has reached an empty space; and this is probably the only information
that the insensible implement can supply. The drill boring through the
rock cannot tell the miner anything about the contents of the cavern
which it has entered; and the case must be the same with the rigid
filament of the Leucopses.
Now that the thread has reached its goal, what does the cell contain?
Mildewed honey, dust and rubbish, a shrivelled larva, or a larva in
good condition? Above all, does it already contain an egg? This last
question calls for a definite answer, but as a matter of fact it is
impossible for the insect to learn anything from a horse-hair on that
most delicate matter, the presence or absence of an egg, a mere atom
of a thing, in that vast apartment. Even admitting some sense of touch
at the end of the drill, one insuperable difficulty would always
remain: that of finding the exact spot where the tiny speck lies in
those spacious and mysterious regions. I go so far as to believe that
the ovipositor tells the insect nothing, or at any rate very little,
of the inside of the cell, whether propitious or not to the
development of the germ. Perhaps each thrust of the instrument,
provided that it meets with no resistance from solid matter, lays the
egg, to whose lot there falls at one time good, wholesome food, at
another mere refuse.
These anomalies call for more conclusive proofs than the rough
deductions drawn from the nature of the horny ovipositor. We must
ascertain in a direct fashion whether the cell into which the auger
has been driven several times over actually contains several occupants
in addition to the larva of the Mason-bee. When the Leucopses had
finished their borings, I waited a few days longer so as to give the
young grubs time to develop a little, which would make my examination
easier. I then moved the tiles to the table in my study, in order to
investigate their secrets with the most scrupulous care. And here such
a disappointment as I have rarely known awaited me. The cells which I
had seen, actually seen, with my own eyes, pierced by the probe two or
three or even four times, contained but one Leucopsis-grub, one alone,
eating away at its Chalicodoma. Others, which had also been repeatedly
probed, contained spoilt remnants, but never a Leucopsis. O holy
patience, give me the courage to begin again! Dispel the darkness and
deliver me from doubt!
I begin again. The Leucopsis-grub is familiar to me; I can recognize
it, without the possibility of a mistake, in the nests of both the
Chalicodoma of the Pebbles and the Chalicodoma of the Sheds. All
through the winter, I rush about, getting my nests from the roofs of
old sheds and the pebbles of the waste-lands; I stuff my pockets with
them, fill my box, load Favier's knapsack; I collect enough to litter
all the tables in my study; and, when it is too cold out of doors,
when the biting mistral blows, I tear open the fine silk of the
cocoons to discover the inhabitant. Most of them contain the Mason in
the perfect state; others give me the larva of the Anthrax; others--
very numerous, these--give me the larva of the Leucopsis. And this
last is alone, always alone, invariably alone. The whole thing is
utterly incomprehensible when one knows, as I know, how many times the
probe entered those cells.
My perplexity only increases when, on the return of summer, I witness
for the second time the Leucopsis' repeated operations on the same
cells and for the second time find a single larva in the compartments
which have been bored several times over. Shall I then be forced to
accept that the auger is able to recognize the cells already
containing an egg and that it thenceforth refrains from laying there?
Must I admit an extraordinary sense of touch in that bit of horse-
hair, or even better, a sort of divination which declares where the
egg lies without having to touch it? But I am raving! There is
certainly something that escapes me; and the obscurity of the problem
is simply due to my incomplete information. O patience, supreme virtue
of the observer, come to my aid once more! I must begin all over again
for the third time.
Until now, my investigations have been made some time after the
laying, at a period when the larva is at least fairly developed. Who
knows? Something perhaps happens, at the very commencement of infancy,
that may mislead me afterwards. I must apply to the egg itself if I
would learn the secret which the grub will not reveal. I therefore
resume my observations in the first fortnight of July, when the
Leucopses are beginning to visit busily both Mason-bee's nests. The
pebbles in the waste-lands supply me with plenty of buildings of the
Chalicodoma of the Walls; the byres scattered here and there in the
fields give me, under their dilapidated roofs, in fragments broken off
with the chisel, the edifices of the Chalicodoma of the Sheds. I am
anxious not to complete the destruction of my home hives, already so
sorely tried by my experiments; they have taught me much and can teach
me more. Alien colonies, picked up more or less everywhere, provide me
with my booty. With my lens in one hand and my forceps in the other, I
go through my collection on the same day, with the prudence and care
which only the laboratory-table permits. The results at first fall far
short of my expectations. I see nothing that I have not seen before. I
make fresh expeditions, after a few days' interval; I bring back fresh
loads of lumps of mortar, until at last fortune smiles upon me.
Reason was not at fault. Each thrust means the laying of an egg when
the probe reaches the cell. Here is a cocoon of the Mason-bee of the
Pebbles with an egg side by side with the Chalicodoma-grub. But what a
curious egg! Never have my eyes beheld the like; and then is it really
the egg of the Leucopsis? Great was my apprehension. But I breathed
again when I found, a couple of weeks later, that the egg had become
the larva with which I was familiar. Those cocoons with a single egg
are as numerous as I can wish; they exceed my wishes: my little glass
receptacles are too few to hold them.
And here are others, more precious ones still, with manifold layings.
I find plenty with two eggs; I find some with three or four; the best-
colonised offer me as many as five. And, to crown my delight, the joy
of the seeker to whom success comes at the last moment, when he is on
the verge of despair, here again, duly furnished with an egg, is a
sterile cocoon, that is to say, one containing only a shrivelled and
decaying larva. All my suspicions are confirmed, down to the most
inconsequent: the egg housed with a mass of putrefaction.
The nests of the Mason-bee of the Walls are the more regular in
structure and are easier to examine, because their base is wide open
once it is separated from the supporting pebble; and it was these
which supplied me with by far the greater part of my information.
Those of the Mason-bee of the Sheds have to be chipped away with a
hammer before one can inspect their cells, which are heaped up anyhow;
and they do not lend themselves anything like so well to delicate
investigations, as they suffer both from the shock and the ill-
treatment.
And now the thing is done: it remains certain that the Leucopsis'
laying is exposed to very exceptional dangers. She can entrust the egg
to sterile cells, without provisions fit to use; she can establish
several in the same cell, though this cell contains nourishment for
one only. Whether they proceed from a single individual returning
several times, by inadvertence, to the same place, or are the work of
different individuals unaware of the previous borings, those multiple
layings are very frequent, almost as much so as the normal layings.
The largest which I have noticed consisted of five eggs, but we have
no authority for looking upon this number as an outside limit. Who
could say, when the perforators are numerous, to what lengths this
accumulation can go? I will set forth on some future occasion how the
ration of one egg remains in reality the ration of one egg, despite
the multiplicity of banqueters.
I will end by describing the egg, which is a white, opaque object,
shaped like a much-elongated oval. One of the ends is lengthened out
into a neck or pedicle, which is as long as the egg proper. This neck
is somewhat wrinkled, sinuous and as a rule considerably curved. The
whole thing is not at all unlike certain gourds with an elongated
paunch and a snake-like neck. The total length, pedicle and all, is
about 3 millimetres. (About one-eighth of an inch.--Translator's
Note.) It is needless to say, after recognizing the grub's manner of
feeding, that this egg is not laid inside the fostering larva. Yet,
before I knew the habits of the Leucopsis, I would readily have
believed that every Hymenopteron armed with a long probe inserts her
eggs into the victim's sides, as the Ichneumon-flies do to the
Caterpillars. I mention this for the benefit of any who may be under
the same erroneous impression.
The Leucopsis' egg is not even laid upon the Mason-bee's larva; it is
hung by its bent pedicle to the fibrous wall of the cocoon. When I go
to work very delicately, so as not to disturb the arrangement in
knocking the nest off its support, and then extract and open the
cocoon, I see the egg swinging from the silken vault. But it takes
very little to make it fall. And so, most often, even though it be
merely the effect of the shock sustained when the nest is removed from
its pebble, I find the egg detached from its suspension-point and
lying beside the larva, to which it never adheres in any
circumstances. The Leucopsis' probe does not penetrate beyond the
cocoon traversed; and the egg remains fastened to the ceiling, in the
crook of some silky thread, by means of its hooked pedicle.
INDEX.
Amazon Ant (see Red Ant).
Ammophila.
Ammophila hirsuta (see Hairy Ammophila).
Ant (see also Black Ant, Red Ant).
Anthidium (see also Cotton-bee, Diadem Anthidium).
Anthophora (see also Hairy-footed Anthophora).
Anthrax (see also Anthrax sinuata).
Anthrax sinuata.
Anthrenus.
Ape.
Aphis.
Baboon.
Bastien.
Bee.
Bembex (see also Bembex rostrata).
Bembex rostrata.
Black Ant.
Blanchard, Emile.
Blue Osmia.
Bombylius.
Bumble-bee.
Butterfly.
Cabbage-caterpillar.
Cagliostro.
Carrier-pigeon.
Castelnau de la Porte, Francis Comte de.
Cat.
Caterpillar (see also Cabbage-caterpillar, Grey Worm, Processionary
Caterpillar, Spurge-caterpillar).
Cerceris (see also Great Cerceris).
Cerceris tuberculata (see Great Cerceris).
Cetonia.
Chalcis.
Chalicodoma (see Mason-bee).
Chalicodoma muraria (see Mason-bee of the Walls).
Chalicodoma pyrenaica, C. pyrrhopeza, C. rufitarsis, C. sicula (see
Mason-bee of the Sheds).
Back to Full Books
|