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I made the acquaintance of the Anthrax in 1855 at Carpentras, at
the time when the life history of the oil beetles was causing me
to search the tall slopes beloved of the Anthophora bees [mason
bees]. Her curious pupae, so powerfully equipped to force an
outlet for the perfect insect incapable of the least effort, those
pupae armed with a multiple plowshare at the fore, a trident at
the rear and rows of harpoons on the back wherewith to rip open
the Osmia bee's cocoon and break through the hard crust of the
hillside, betokened a field that was worth cultivating. The
little that I said about her at the time brought me urgent
entreaties: I was asked for a circumstantial chapter on the
strange fly. The stern necessities of life postponed to an ever
retreating future my beloved investigations, so miserably stifled.
Thirty years have passed; at last, a little leisure is at hand;
and here, in the harmas of my village, with an ardor that has in
no wise grown old, I have resumed my plans of yore, still alive
like the coal smoldering under the ashes. The Anthrax has told me
her secrets, which I in my turn am going to divulge. Would that I
could address all those who cheered me on this path, including
first and foremost the revered Master of the Landes [Leon Dufour].
But the ranks have thinned, many have been promoted to another
world and their disciple lagging behind them can but record, in
memory of those who are no more, the story of the insect clad in
deepest mourning.

In the course of July, let us give a few sideward knocks to the
bracing pebbles and detach the nests of the Chalicodoma of the
Walls [a mason bee] from their supports. Loosened by the shock,
the dome comes off cleanly, all in one piece. Moreover--and this
is a great advantage--the cells come into view wide open on the
base of the exposed nest, for at this point they have no other
wall than the surface of the pebble. In this way, without any
scraping, which would be wearisome work for the operator and
dangerous to the inhabitants of the dome, we have all the cells
before our eyes, together with their contents, consisting of a
silky, amber-yellow cocoon, as delicate and translucent as an
onion peeling. Let us split the dainty wrapper with the scissors,
chamber by chamber, nest by nest. If fortune be at all
propitious, as it always is to the persevering, we shall end by
finding that the cocoons harbor two larvae together, one more or
less faded in appearance, the other fresh and plump. We shall
also find some, no less plentiful, in which the withered larva is
accompanied by a family of little grubs wriggling uneasily around

Examination at once reveals the tragedy that is happening under
the cover of the cocoon. The flacid and faded larva is the mason
bee's. A month ago, in June, having finished its mess of honey,
it wove its silken sheath for a bedchamber wherein to take the
long sleep which is the prelude to the metamorphosis. Bulging
with fat, it is a rich and defenseless morsel for whoever is able
to reach it. Then, in spite of apparently insurmountable
obstacles, the mortar wall and the tent without an opening, the
flesh-eating larvae appeared in the secret retreat and are now
glutting themselves on the sleeper. Three different species take
part in the carnage, often in the same nest, in adjoining cells.
The diversity of shapes informs us of the presence of more than
one enemy; the final stage of the creatures will tell us the names
and qualities of the three invaders.

Forestalling the secrets. of the future for the sake of greater
clearness, I will anticipate the actual facts and come at once to
the results produced. When it is by itself on the body of the
mason bee's larva, the murderous grub belongs either to Anthrax
trifasciata, MEIGEN, or to Leucospis gigas, FAB. But, if numerous
little worms, often a score and more, swarm around the victim,
then it is a Chalcidid's family which we have before us. Each of
these ravagers shall have its biography. Let us begin with the

And first the grub, as it is after consuming its victim, when it
remains the sole occupant of the mason bee's cocoon. It is a
naked worm, smooth, legless and blind, of a creamy dead white,
each segment a perfect ring, very much curved when at rest, but
with the tendency to become almost straight when disturbed.
Through the diaphanous skin, the lens distinguishes patches of
fat, which are the cause of its characteristic coloring. When
younger, as a tiny grub a few millimeters long, it is streaked
with two different kinds of stains, some white, opaque and of a
creamy tint, others translucent and of the palest amber. The
former come from adipose masses in course of formation; the second
from the nourishing fluid or from the blood which laves those

Including the head, I count thirteen segments. In the middle of
the body these segments are well marked, being separated by a
slight groove; but in the forepart they are difficult to count.
The head is small and is soft, like the rest of the body, with no
sign of any mouth parts even under the close scrutiny of the lens.
It is a white globule, the size of a tiny pin's head and continued
at the back by a pad a little larger, from which it is separated
by a scarcely appreciable crease. The whole is a sort of nipple
swelling slightly on the upper surface; and its double structure
is so difficult to perceive that at first we take it for the
animal's head alone, though it includes both the head and the
prothorax, or first segment of the thorax.

The mesothorax, or middle segment of the thorax, which is two or
three times larger in diameter, is flattened in front and
separated from the nipple formed by the prothorax and the head by
a deep, narrow, curved fissure. On its front surface are two pale
red stigmata, or respiratory orifices, placed pretty close
together. The metathorax, or last segment of the thorax, is a
little larger still in diameter and protrudes. These abrupt
increases in circumference result in a marked hump, sloping
sharply towards the front. The nipple of which the head forms
part is set at the bottom of this hump.

After the metathorax, the shape becomes regular and cylindrical,
while decreasing slightly in girth in the last two or three
segments. Close to the line of separation of the last two rings,
I am able to distinguish, not without difficulty, two very small
stigmata, just a little darker in color. They belong to the last
segment. In all, four respiratory orifices, two in front and two
behind, as is the rule among Flies. The length of the full sized
larva is 15 to 20 millimeters and its breadth 5 to 6.

Remarkable in the first place by the protuberance of its thorax
and the smallness of its head, the grub of the Anthrax acquires
exceptional interest by its manner of feeding. Let us begin by
observing that, deprived of all, even the most rudimentary walking
apparatus, the animal is absolutely incapable of shifting its
position. If I disturb its rest, it curves and straightens itself
in turns by a series of contractions, it tosses about violently
where it lies, but does not manage to progress. It fidgets and
gets no farther. We shall see later the magnificent problem
raised by this inertness.

For the moment, a most unexpected fact claims all our attention.
I refer to the extreme readiness with which the Anthrax' larva
quits and returns to the Chalicodoma grub on which it is feeding.
After witnessing flesh eating larvae at hundreds and hundreds of
meals, I suddenly find myself confronted with a manner of eating
that bears no relation to anything which I have seen before. I
feel myself in a world that baffles my old experience. Let us
recall the table manners of a larva living on prey, the
Ammophila's for instance, when devouring its caterpillar. A hole
is made in the victim's side; and the head and neck of the
nursling dive deep into the wound, to root luxuriously among the
entrails. There is never a withdrawal from the gnawed belly,
never a recoil to interrupt the feast and to take breath awhile.
The vivacious animal always goes forward, chewing, swallowing,
digesting, until the caterpillar's skin is emptied of its
contents. Once seated at table, it does not budge as long as the
victuals last. To tease it with a straw is not always enough to
induce it to withdraw its head outside the wound; I have to use
violence. When removed by force and then left to its own devices,
the creature hesitates for a long time, stretches itself and
mouths around, without trying to open a passage through a new
wound. It needs the attacking point that has just been abandoned.
If it finds the spot, it makes its way in and resumes the work of
eating; but its future is jeopardized from this time forward, for
the game, now perhaps tackled at inopportune points, is liable to
go bad.

With the Anthrax' grub, there is none of this mangling, none of
this persistent clinging to the entrance wound. I have but to
tease it with the tip of a hair pencil and forthwith it retires;
and the lens reveals no wound at the abandoned spot, no such
effusion of blood as there would be if the skin were perforated.
When its sense of security is restored, the grub once more applies
its pimple head to the fostering larva, at any point, no matter
where; and, so long as my curiosity does not prevent it, keeps
itself fixed there, without the least effort, or the least
perceptible movement that could account for the adhesion. If I
repeat the touch with the pencil, I see the same sudden retreat
and, soon after, the same contact just as readily renewed.

This facility for gripping, quitting and regripping, now here, now
there and always without a wound, the part of the victim whence
the nourishment is drawn tells us of itself that the mouth of the
Anthrax is not armed with mandibular fangs capable of digging into
the skin and tearing it. If the flesh were gashed by any such
pincers, one or two attempts would be necessary before they could
be released or reapplied; besides, each point bitten would display
a lesion. Well, there is nothing of the kind: a conscientious
examination through the magnifying glass shows conclusively that
the skin is intact; the grub glues its mouth to its prey or
withdraws it with an ease that can only be explained by a process
of simple contact. This being so, the Anthrax does not chew its
food as do the other carnivorous grubs; it does not eat, it

This method of taking nourishment implies an exceptional apparatus
of the mouth, into which it behooves us to inquire before
continuing. My most powerful magnifying glass at last discovers,
at the center of the pimple head, a small spot of an amber-russet
color; and that is all. For a more exhaustive examination we will
employ the microscope. I cut off the strange pimple with the
scissors, wash it in a drop of water and place it on the object
slide. The mouth now stands revealed as a round spot which, for
hue and for the smallness of its size, may be compared with the
front stigmata. It is a small conical crater, with sides of a
pale yellowish-red and with faint, more or less concentric lines.
At the bottom of this funnel is the opening of the gullet, itself
tinted red in front and promptly spreading into a cone at the
back. There is not the slightest trace of mandibular fangs, of
jaws, of mouth parts for seizing and grinding. Everything is
reduced to the bowl shaped opening, with a delicate lining of
horny texture, as is shown by the amber hue and the concentric
streaks. When I look for some term to designate this digestive
entrance, of which so far I know no other example, I can find only
that of a sucker or cupping glass. Its attack is a mere kiss, but
what a perfidious kiss!

We know the machine; now let us see the working. To facilitate
observation, I shifted the newborn Anthrax grub, together with the
Chalicodoma grub, its wet nurse, from the natal cell into a glass
tube. I was thus able, by employing as many tubes as I wanted, to
follow from start to finish, in all its most intimate details, the
strange repast which I am going to describe.

The worm is fixed by its sucker to any convenient part of the
nurse, plump and fat as butter. It is ready to break off its kiss
suddenly, should anything disquiet it, and to resume it as easily
when tranquillity is restored. No Lamb enjoys greater liberty
with its mother's teat. After three or four days of this contact
of the nurse and nursling, the former, at first replete and
endowed with the glossy skin that is a sign of health, begins to
assume a withered aspect. Her sides fall in, her fresh color
fades, her skin becomes covered with little folds and gives
evidence of an appreciable shrinking in this breast which, instead
of milk, yields fat and blood. A week is hardly past before the
progress of the exhaustion becomes startlingly rapid. The nurse
is flabby and wrinkled, as though borne down by her own weight,
like a very slack object. If I move her from her place, she flops
and sprawls like a half-filled water bottle over the new
supporting plane. But the Anthrax' kiss goes on emptying her:
soon she is but a sort of shriveled lard bag, decreasing from hour
to hour, from which the sucker draws a few last oily drains. At
length, between the twelfth and the fifteenth day, all that
remains of the larva of the mason bee is a white granule, hardly
as large as a pin's head.

This granule is the water bottle drained to the last drop, is the
nurse's breast emptied of all its contents. I soften the meager
remnant in water; then, keeping it still immersed, I blow into it
through an extremely attenuated glass tube. The skin fills out,
distends and resumes the shape of the larva, without there being
an outlet anywhere for the compressed air. It is intact,
therefore; it is free of any perforation, which would be forthwith
revealed under the water by an escape of gas. And so, under the
Anthrax' cupping glass, the oily bottle has been drained by a
simple transpiration through the membrane; the substance of the
nurse grub has been transfused into the body of the nursling by a
process akin to that known in physics as endosmosis. What should
we say to a method of being suckled by the mere application of the
mouth to a teatless breast? What we see here may be compared with
that: without any outlet, the milk of the Chalicodoma grub passes
into the stomach of the Anthrax' larva.

Is it really an instance of endosmosis? Might it not rather be
atmospheric pressure that stimulates the flow of nourishing fluids
and distils them into the Anthrax' cup-shaped mouth, working, in
order to create a vacuum. almost like the suckers of the
Cuttlefish? All this is possible, but I shall refrain from
deciding, preferring to assign a large share to the unknown in
this extraordinary method of nutrition. It ought, I think, to
provide physiologists with a field of research in which new views
on the hydrodynamics of live fluids might well be gleaned; and
this field trenches upon others that would also yield rich
harvests. The brief span of my days compels me to set the problem
without seeking to solve it.

And the second problem is this: the Chalicodoma grub destined to
feed the Anthrax is without a wound of any kind. The mother of
the tiny larva is a feeble Fly deprived of whatsoever weapon
capable of injuring her offspring's prey. Moreover, she is
absolutely powerless to penetrate the mason bee's fortress,
powerless as a fluff of down against a rock. On this point there
is no doubt: the future wet nurse of the Anthrax has not been
paralyzed as are the live provisions collected by the Hunting
Wasps; she has received no bite nor scratch nor contusion of any
sort; she has experienced nothing out of the common: in short, she
is in her normal state. The billeted nursling arrives, we shall
presently see how; he arrives, scarcely visible, almost defying
the scrutiny of the lens; and, having made his preparations, he
installs himself, he, the atom, upon the monstrous nurse, whom he
is to drain to the very husk. And she, not paralyzed by a
preliminary vivisection, endowed with all her normal vitality,
lets him have his way, lets herself be sucked dry, with the utmost
apathy. Not a tremor in her outraged flesh, not a quiver of
resistance. No corpse could show greater indifference to the bite
which it receives.

Ah, but the maggot has chosen the hour of attack with traitorous
cunning! Had it appeared upon the scene earlier, when the larva
was consuming its store of honey, things of a surety would have
gone badly with it. The assaulted one, feeling herself bled to
death by that ravenous kiss, would have protested with much
wriggling of body and grinding of mandibles. The position would
have ceased to be tenable and the intruder would have perished.
But at this hour all danger has disappeared. Enclosed in its
silken tent, the larva is seized with the lethargy that precedes
the metamorphosis. Its condition is not death, but neither is it
life. It is an intermediary condition; it is almost the latent
vitality of grain or egg. Therefore there is no sign of
irritation on the larva's part under the needle with which I stir
it and still less under the sucker of the Anthrax grub, which is
able to drain the affluent breast in perfect safety.

This lack of resistance, induced by the torpor of the
transformation, appears to me necessary, in view of the weakness
of the nursling as it leaves the egg, whenever the mother is
herself incapable of depriving the victim of the power of self
defense. And so the nonparalyzed larvae are attacked during the
period of the nymphosis. We shall soon see other instances of

Motionless though it be, the Chalicodoma grub is none the less
alive. The primrose tint and the glossy skin are unequivocal
signs of health: Were it really dead, it would, in less than
twenty-four hours, turn a dirty brown and, soon after, decompose
into a fluid putrescence. Now here is the marvelous thing: during
the fortnight, roughly, that the Anthrax' meal lasts, the butter
color of the larva, an unfailing symptom of the presence of life,
continues unaltered and does not change into brown, the sign of
putrefaction, until hardly anything remains; and even then the
brown hue is often absent. As a rule, the look of live flesh is
preserved until the final pellet, formed of the skin, the sole
residue, makes its appearance. This pellet is white, with not a
speck of tainted matter, proving that life persists until the body
is reduced to nothing.

We here witness the transfusion of one animal into another, the
change of Chalicodoma substance into Anthrax substance; and, as
long as the transfusion is not complete, as long as the eaten has
not disappeared altogether and become the eater, the ruined
organism fights against destruction. What manner of life is this,
which may be compared with the life of a night light whose
extinction is not accomplished until the last drop of oil has
burnt away? How is any creature able to fight against the final
tragedy of corruption up to the last moment in which a nucleus of
matter remains as the seat of vital energy? The forces of the
living creature are here dissipated not through any disturbance of
the equilibrium of those forces, but for the want of any point of
application for them: the larva dies because materially there is
no more of it.

Can we be in the presence of the diffusive life of the plant, a
life which persists in a fragment? By no means: the grub is a
more delicate organic structure. There is unity between the
several parts; and none of them can be jeopardized without
involving the ruin of the others. If I myself give the larva a
wound, if I bruise it, the whole body very soon turns brown and
begins to rot. It dies and decomposes by the mere prick of a
needle; it keeps alive, or at least preserves the freshness of the
live tissues, so long as it is not entirely emptied by the
Anthrax' sucker. A nothing kills it; an atrocious wasting does
not. No, I fail to understand the problem; and I bequeath it to

All that I can see by way of a glimpse--and even then I put
forward my suspicions with extreme reserve--all that I am
permitted to surmise is reduced to this: the substance of the
sleeping larva as yet has no very definite static existence; it is
like the raw materials collected for a building; it is waiting for
the elaboration that is to make a bee of it. To mould those
shapeless lumps of the future insect, the air, that prime adjuster
of living things, circulates among them, passing through a network
of ducts. To organize them, to direct the placing of them, the
nervous system, the embryo of the animal, distributes its
ramifications over them. Nerve and air duct, therefore, are the
essentials; the rest is so much material in reserve for the
process of the metamorphosis. As long as that material is not
employed, as long as it has not acquired its final equilibrium, it
can grow less and less; and life, though languishing, will
continue all the same on the express condition that the
respiratory organs and the nervous filaments be respected. It is
as it were the flame of the lamp, which, whether full or empty,
continues to give light so long as the wick is soaked in oil.
Nothing but fluids, the plastic materials held in reserve, can be
distilled by the Anthrax' sucker through the unpierced skin of the
grub; no part of the respiratory and nervous systems passes. As
the two essential functions remain unscathed, life goes on until
exhaustion is completed. On the other hand, if I myself injure
the larva, I disturb the nervous or air conducting filaments; and
the bruised part spreads a taint, followed by putrefaction, all
over the body.

I have elsewhere, speaking of the Scolia [a digger wasp] devouring
the Cetonia grub, enlarged upon this refined art of eating which
consists in consuming the prey while killing it only at the last
mouthfuls. The Anthrax has the same requirements as his
competitors who dine off fresh viands. He needs meat of that day,
taken from a single joint that has to last a fortnight without
going bad. His method of consuming reaches the highest level of
art: he does not cut into his prey, he sips it little by little
through his sucker. In this way, any dangerous risk is averted.
Whether he imbibe at this spot or at that, even if he abandon the
sucking process and resume it later, by no accident can he ever
attack that which it is incumbent upon him to respect lest
corruption supervene. The others have a fixed position on the
victim, a place at which their mandibles have to bite and enter.
If they move away from it, if they miss the appointed path, they
imperil their existence. The Anthrax, more highly favored, puts
his mouth where it suits him; he leaves off when he pleases and
when he pleases starts again.

Unless I labor under a delusion, I think that I see the necessity
for this privilege. The egg of the carnivorous burrower is firmly
fixed on the victim at a point which varies considerably, it is
true, according to the nature of the prey, but which is uniform
for the same species of prey; moreover--and this is an important
condition--the point of adhesion of that egg is always the head,
whereas the egg of a bee, of the Osmia, for instance, is fixed to
the mess of honey by the hinder end. When hatched, the new born
Wasp grub has not to choose for itself, at its risk and peril, the
suitable point at which to take the first cut in the quarry
without fear of killing it too quickly: all that it need do is to
bite at the spot where it has just been born. The mother, with
her unfailing instinct, has already made the dangerous choice; she
has stuck her egg on the propitious spot and, by the very act of
doing so, marked out the course for the inexperienced grub to
follow. The tact of ripe age here guides the young larva's
behavior at table.

The conditions are very different in the Anthrax' case. The egg
is not placed upon the victuals, it is not even laid in the mason
bee's cell. This is the natural consequence of the mother's
feeble frame and of her lack of any instrument, such as a probe or
auger, capable of piercing the mortar wall. It is for the newly
hatched grub to make its own way into the dwelling. It enters,
finds itself in the presence of ample provisions, the larva of the
mason bee. Free of its actions, it is at liberty to attack the
prey where it chooses; or rather the attacking point will be
decided at haphazard by the first contact of the mouth in quest of
food. Grant this mouth a set of carving tools, jaws and
mandibles; in short, suppose the grub of the Fly to possess a
manner of eating similar to that of the other carnivorous larvae;
and the nursling is at once threatened with a speedy death. He
will split open his nurse's belly, he will dig without any rule to
guide him, he will bite at random, essentials as well as
accessories; and, from one day to the next, he will set up
gangrene in the violated mass, even as I myself do when I give it
a wound. For the lack of an attacking point prescribed for him at
birth, he will perish on the damaged provisions. His freedom of
action will have killed him.

Certainly, liberty is a noble attribute, even in an insignificant
grub; but it also has its dangers everywhere. The Anthrax escapes
the peril only on the condition of being, so to speak, muzzled.
His mouth is not a fierce forceps that tears asunder; it is a
sucker that exhausts but does not wound. Thus restrained by this
safety appliance, which changes the bite into a kiss, the grub has
fresh victuals until it has finished growing, although it knows
nothing of the rules of methodical consumption at a fixed point
and in a predetermined direction.

The considerations which I have set forth seem to me strictly
logical: the Anthrax, owing to the very fact that he is free to
take his nourishment where he pleases on the body of the fostering
larva, must, for his own protection, be made incapable of opening
his victim's body. I am so utterly convinced of this harmonious
relation between the eater and the eaten that I do not hesitate to
set it up as a principle. I will therefore say this: whenever the
egg of any kind of insect is not fastened to the larva destined
for its food, the young grub, free to select the attacking point
and to change it at will, is as it were muzzled and consumes its
provisions by a sort of suction, without inflicting any
appreciable wound. This restriction is essential to the
maintenance of the victuals in good condition. My principle is
already supported by examples many and various, whose depositions
are all to the same effect. The witnesses include, after the
Anthrax, the Leucospis [a parasitic insect] and his rivals, whose
evidence we shall hear presently; the Ephialtes mediator [an
Ichneumon fly], who feeds, in the dry brambles, on the larva of
the Black Psen [a digger wasp]; the Myodites, that strange, fly-
shaped beetle whose grub consumes the larva of the cockchafer.
All--flies, ichneumon flies and beetles--scrupulously spare their
foster mother; they are careful not to tear her skin, so that the
vessel may keep its liquid good to the last.

The wholesomeness of the victuals is not the only condition
imposed: I find a second, which is no less essential. The
substance of the fostering larva must be sufficiently fluid to
ooze through the unbroken skin under the action of the sucker.
Well, the necessary fluidity is realized as the time of the
metamorphosis draws near. When they wished Medea to restore
Pelias to the vigor of youth, his daughters cut the old king's
body to pieces and boiled it in a cauldron, for there can be no
new existence without a prior dissolution. We must pull down
before we can rebuild; the analysis of death is the first step
towards the synthesis of life. The substance of the grub that is
to be transformed into a bee begins, therefore, by disintegrating
and dissolving into a fluid broth. The materials of the future
insect are obtained by a general recasting. Even as the founder
puts his old bronzes into the melting pot in order afterwards to
cast them in a mould whence the metal will issue in a different
shape, so life liquefies the grub, a mere digesting machine, now
thrown aside, and out of its running matter produces the perfect
insect, bee, butterfly or beetle, the final manifestation of the
living creature.

Let us open a Chalicodoma grub under the microscope, during the
period of torpor. Its contents consists almost entirely of a
liquid broth, in which swim numberless oily globules and a fine
dust of uric acid, a sort of off-throw of the oxidized tissues. A
flowing thing, shapeless and nameless, is all that the animal is,
if we add abundant ramified air ducts, some nervous filaments and,
under the skin, a thin layer of muscular fibers. A condition of
this kind accounts for a fatty transpiration through the skin when
the Anthrax' sucker is at work. At any other time, when the larva
is in the active period or else when the insect has reached the
perfect stage, the firmness of the tissues would resist the
transfusion and the suckling of the Anthrax would become a
difficult matter, or even impossible. In point of fact, I find
the grub of the fly established, in the vast majority of cases, on
the sleeping larva and sometimes, but rarely, on the pupa. Never
do I see it on the vigorous larva eating its honey; and hardly
ever on the insect brought to perfection, as we find it enclosed
in its cell all through the autumn and winter. And we can say the
same of the other grub eaters that drain their victims without
wounding them: all are engaged in their death dealing work during
the period of torpor, when the tissues are fluidified. They empty
their patient, who has become a bag of running grease with a
diffused life; but not one, among those I know, reaches the
Anthrax' perfection in the art of extraction.

Nor can any be compared with the Anthrax as regards the means
brought into play in order to leave the cell. These others, when
they become perfect insects, have implements for sapping and
demolishing, stout mandibles, capable of digging the ground, of
pulling down clay partition walls and even of reducing the mason
bee's tough cement to powder. The Anthrax, in her final form, has
nothing like this. Her mouth is a short, soft proboscis, good at
most for soberly licking the sugary exudations of the flowers; her
slim legs are so feeble that to move a grain of sand were an
excessive task for them, enough to strain every joint; her great,
stiff wings, which must remain full spread, do not allow her to
slip through a narrow passage; her delicate suit of downy velvet,
from which you take the bloom by merely breathing on it, could not
withstand the rough contact of the gallery of a mine. Unable
herself to enter the Mason bee's cell to lay her egg, she cannot
leave it either, when the time comes to free herself and appear in
broad daylight in her wedding dress. The larva, on its side, is
powerless to prepare the way for the coming flight. That buttery
little cylinder, owning no tools but a sucker so flimsy that it
barely arrives at substance and so small that it is almost a
geometrical point, is even weaker than the adult insect, which at
least flies and walks. The Mason bee's cell represents to it a
granite cave. How to get out? The problem would be insoluble to
those two incapables, if nothing else played its part.

Among insects, the nymph, or pupa, the transition stage between
the larval and the adult form, is generally a striking picture of
every weakness of a budding organism. A sort of mummy tight bound
in swaddling clothes, motionless and impassive, it awaits the
resurrection. Its tender tissues flow in every direction; its
limbs, transparent as crystal, are held fixed in their place,
along the side, lest a movement should disturb the exquisite
delicacy of the work in course of accomplishment. Even so, to
secure his recovery, is a broken boned patient held captive in the
surgeon's bandages. Absolute stillness is necessary in both
cases, lest they be crippled or even die.

Well, here, by a strange inversion that confuses all our views on
life, a Cyclopean task is laid upon the nymph of the Anthrax. It
is the nymph that has to toil, to strive, to exhaust itself in
efforts to burst the wall and open the way out. To the embryo
falls the desperate duty, which shows no mercy to the nascent
flesh; to the adult insect the joy of resting in the sun. This
transposition of functions has as its result a well sinker's
equipment in the nymph, an eccentric, complicated equipment which
nothing suggested in the larva and which nothing recalls in the
perfect insect. The set of tools includes an assortment of
plowshares, gimlets, hooks and spears and of other implements that
are not found in our trades nor named in our dictionaries. Let us
do our best to describe the strange piercing gear.

In a fortnight at most, the Anthrax has consumed the Chalicodoma
grub, whereof naught remains but the skin, gathered into a white
granule. By the time that July is nearly over, it becomes rare to
find any nurslings left upon their nurses. From this period until
the following May, nothing fresh happens. The Anthrax retains its
larval shape without any appreciable change and lies motionless in
the mason bee's cocoon, beside the pellet remains. When the fine
days of May arrive, the grub shrivels and casts its skin and the
nymph appears, fully clad in a stout, reddish, horny hide.

The head is round and large, separated from the thorax by a
strangulated furrow, crowned on top and in front with a sort of
diadem of six hard, sharp, black spikes, arranged in a semicircle
whose concave side faces downward. These spikes decrease slightly
in length from the summit to the ends of the arch. Taken
together, they suggest the radial crowns which we see the Roman
emperors of the Decadence wear on the medals. This six-fold
plowshare is the chief excavating tool. Lower down, on the median
line, the instrument is finished off with a separate group of two
small black spikes, placed close together.

The thorax is smooth, the wing cases large, folded under the body
like a scarf and coming almost to the middle of the abdomen. This
has nine segments, of which four, starting with the second, are
armed, on the back, down the middle, with a belt of little horny
arches, pale brown in color, drawn up parallel to one another, set
in the skin by their convex surfaces and finishing at both ends
with a hard, black point. Altogether, the belt thus forms a
double row of little thorns, with a hollow in between. I count
about twenty-five twin-toothed arches to one segment, which gives
a total of two hundred spikes for the four rings thus armed.

The use of this rasp, or grater, is obvious: it gives the nymph a
purchase on the wall of its gallery as the work proceeds. Thus
anchored on a host of points, the stern pioneer is able to hit the
obstacle harder with its diadem of awls. Moreover, to make it
more difficult for the instrument to recoil, long, stiff bristles,
pointing backwards, are scattered here and there among the
climbing belts. There are some besides on the other segments,
both on the ventral and the dorsal surface. On the flanks, they
are thicker and arranged as it were in clusters.

The sixth segment carries a similar belt, but a much less powerful
one, consisting of a single row of unassuming thorns. The belt is
weaker still on the seventh segment; lastly, on the eighth, it is
reduced to a mere rough brown shading. Commencing with the sixth,
the rings decrease in width and the abdomen ends in a cone, the
extremity of which, formed of the ninth segment, constitutes a
weapon of a new kind. It is a sheaf of eight brown spikes. The
last two exceed the others in length and stand out from the group
in a double terminal plowshare.

There is a round air hole in front, on either side of the thorax,
and similar stigmata on the flanks of each of the first seven
abdominal segments. When at rest, the nymph is curved into a bow.
When about to act, it suddenly unbends and straightens itself. It
measures 15 to 20 millimeters long and 4 to 5 millimeters across.

Such is the strange perforating machine that is to prepare an
outlet for the feeble Anthrax through the Mason bee's cement. The
structural details, so difficult to explain in words, may be
summed up as follows: in front, on the forehead, a diadem of
spikes, the ramming and digging tool; behind, a many bladed
plowshare which fits into a socket and allows the pupa to slacken
suddenly in readiness for an attack on the barrier which has to be
demolished; on the back, four climbing belts, or graters, which
keep the animal in position by biting on the walls of the tunnel
with their hundreds of teeth; and, all over the body, long, stiff
bristles, pointing backwards, to prevent falls or recoils.

A similar structure exists in the other species of Anthrax with
slight variations of detail. I will confine myself to one
instance, that of Anthrax sinuata, who thrives at the cost of
Osmia tricornis. Her nymph differs from that of Anthrax
trifasciata, the Anthrax of the mason bee, in possessing less
powerful armor. Its four climbing belts consist of only fifteen
to seventeen double spiked arches, instead of twenty-five; also,
the abdominal segments, from the sixth onwards, are supplied
merely with stiff bristles, without a trace of horny spikes. If
the evolution of the various Anthrax flies were better known to
us, the number of these arches would, I believe, be of great
service to entomology in the differentiation of species. I see it
remaining constant for any given species, with marked variations
between one species and another. But this is not my business: I
merely call the attention of the classifiers to this field of
study and pass on.

About the end of May, the coloring of the nymph, hitherto a light
red, alters greatly and forecasts the coming transformation. The
head, the thorax and the scarf formed by the wings become a
handsome, shiny black. A dark band shows on the back of the four
segments with their two rows of spikes; three spots appear on the
two next rings; the anal armor becomes darker. In this manner we
foresee the black livery of the coming insect. The time has
arrived for the pupa to work at the exit gallery.

I was anxious to see it in action, not under natural conditions,
which would be impracticable, but in a glass tube in which I
confine it between two thick stoppers of sorghum pith. The space
thus marked off is about the same size as the natal cell. The
partitions front and back, although not so stout as the
Chalicodoma's masonry, are nevertheless firm enough not to yield
except to prolonged efforts; on the other hand, the side walls are
smooth and the toothed belts will not be able to grip them: a most
unfavorable condition for the worker. No matter: in the space of
a single day, the pupa pierces the front partition, three quarters
of an inch thick. I see it fixing its double plowshare against
the back partition, arching into a bow and then suddenly releasing
itself and striking the plug in front of it with its barbed
forehead. Under the impact of the spikes, the sorghum slowly
crumbles to pieces. It is slow in coming away; but it comes away
all the same, atom by atom. At long intervals, the method
changes. With its crown of awls driven into the pith, the animal
frets and fidgets, sways on the pivot of its anal armor. The work
of the auger follows that of the pickaxe. Then the blows
recommence, interspersed with periods of rest to recover from the
fatigue. At last, the hole is made. The pupa slips into it, but
does not pass through entirely: the head and thorax appear
outside; the abdomen remains held in the gallery.

The glass cell, with its lack of supports at the side, has
certainly perplexed my subject, which does not seem to have made
use of all its methods. The hole through the sorghum is wide and
irregular; it is a clumsy breach and not a gallery. When made
through the mason bee's walls, it is cylindrical, fairly neat and
exactly of the animal's diameter. So I hope that, under natural
conditions, the pupa does not give quite so many blows with the
pickaxe and prefers to work with the drill.

Narrowness and evenness in the exit tunnel are necessary to it.
It always remains half caught in it and even pretty securely fixed
by the graters on its back. Only the head and thorax emerge into
the outer air. This is a last precaution for the final
deliverance. A fixed support is, in fact, indispensable to the
Anthrax for issuing from her horny sheath, unfurling her great
wings and extricating her slender legs from their scabbards. All
this very delicate work would be endangered by any lack of

The pupa, therefore, remains fixed by the graters of its back in
the narrow exit gallery and thus supplies the stable equilibrium
essential to the new birth. All is ready. It is time now for the
great act. A transversal cleft makes its appearance on the
forehead, at the bottom of the perforating diadem; a second, but
longitudinal slit divides the skull in two and extends down the
thorax. Through this cross-shaped opening, the Anthrax suddenly
appears, all moist with the humors of life's laboratory. She
steadies herself upon her trembling legs, dries her wings and
takes to flight, leaving at the window of the cell her nymphal
slough, which keeps intact for a very long period. The sand-
colored fly has five or six weeks before her, wherein to explore
the clay nests amid the thyme and to take her small share of the
joys of life. In July, we shall see her once more, busy this time
with the entrance into the cell, which is even stranger than the


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