THE CRIOCERES
I am a stubborn disciple of St. Thomas the Apostle and, before I agree
to anything, I want to see and touch it, not once, but twice, thrice,
an indefinite number of times, until my incredulity bows beneath the
weight of evidence. Well, the Rhynchites[1] have told us that the
build does not determine the instincts, that the tools do not decide
the trade. And now, yes, the Crioceres come and add their testimony. I
question three of them, all common, too common, in my paddock. At the
proper season, I have them before my eyes, without searching for them,
whenever I want to ask them for information.
[Footnote 1: A genus of Weevils, the essays upon whom will appear in a
later volume to be entitled _The Life of Weevil_.--_Translator's
Note_.]
The first is the Crioceris of the Lily, or Lily-beetle. Since Latin
words offend our modesty let us just once mention her scientific name,
_Crioceris merdigera_, LIN., without translating it, or, above all,
repeating it. Decency forbids. I have never been able to understand
why natural history need inflict upon a lovely flower or an engaging
animal an odious name.
As a matter of fact, our Crioceris, so ill-treated by the
nomenclators, is a sumptuous creature. She is nicely shaped, neither
too large nor too small, and a beautiful coral red, with jet-black
head and legs. Everybody knows her who in the spring has ever glanced
at the lily, when its stem is beginning to show in the centre of the
rosette of leaves. A Beetle, of less than the average size and
coloured sealing-wax red, is perched up on the plant. Your hand goes
out to seize her. Forthwith, paralysed with fright, she drops to the
ground.
Let us wait a few days and return to the lily, which is gradually
growing taller and beginning to show its buds, gathered together in a
bundle. The red insect is still there. Further, the leaves, which are
seriously bitten into, are reduced to tatters and soiled with little
heaps of greenish ordure. It looks as if some witchcraft had mashed up
the leaves and then splashed the mess all over the place.
Well, this filth moves, travels slowly along. Let us overcome our
repugnance and poke the heaps with a straw. We uncover, indeed we
unclothe an ugly, pot-bellied, pale-orange larva. It is the grub of
the Crioceris.
The origin of the garment of which we have just stripped it would be
unmentionable, save in the world of the insect, that manufacturer
devoid of shame. This doublet is, in fact, obtained from the
creature's excretions. Instead of evacuating downwards, on the
superannuated principle, the Crioceris' larva evacuates upwards and
receives upon its back the waste products of the intestine, materials
which move from back to front as each fresh pat is dabbed upon the
others. Reaumur has complacently described how the quilt moves forward
from the tail to the head by wriggling along inclined planes, making
so many dips in the undulating back. There is no need to return to
this stercoral mechanism after the master has done with it.
We now know the reasons that procured the Lily-beetle an ignominious
title, confined to the official records: the grub makes itself an
overcoat of its excrements.
Once the garment is completed so as to cover the whole of the
creature's dorsal surface, the clothing-factory does not cease work on
that score. At the back a fresh hem is added from moment to moment;
but the overlapping superfluity in front drops off of its own weight
at the same time. The coat of dung is under continual repair, being
renovated and lengthened at one end as it wears and grows shorter at
the other.
Sometimes also the stuff is too thick and the heap capsizes. The
denuded grub recks nothing of the lost overcoat; its obliging
intestine repairs the disaster without delay.
Whether by reason of the clipping that results from the excessive
length of a piece which is always on the loom, or of accidents that
cause a part or the whole of the load to fall off, the grub of the
Crioceris leaves accumulations of dirt in its track, till the lily,
the symbol of purity, becomes a very cess-pool. When the leaves have
been browsed, the stem next loses its cuticle, thanks to the nibbling
of the grub, and is reduced to a ragged distaff. The flowers even,
which have opened by now, are not spared: their beautiful ivory
chalices are changed into latrines.
The perpetrator of the misdeed embarks on his career of defilement
early. I wanted to see him start, to watch him lay the first course of
his excremental masonry. Does he serve an apprenticeship? Does he work
badly at first, then a little better and then well? I now know all
about it: there is no noviciate, there are no clumsy attempts; the
workmanship is perfect from the outset, the product ejected spreads
over the hinder part. Let me tell you what I saw.
The eggs are laid in May, on the under surface of the leaves, in short
trails averaging from three to six. They are cylindrical, rounded at
both ends, of a bright orange-red, glossy and varnished with a
glutinous wash which makes them stick to the leaves throughout their
length. The hatching takes ten days. The shell of the egg, now a
little wrinkled, but still of a bright orange colour, retains its
position, so that the group of eggs, apart from its slightly withered
appearance, remains just as it was.
The young larva measures a millimetre and a half[2] in length. The
head and legs are black, the rest of the body a dull amber-red. On the
first segment of the thorax is a brown sash, interrupted in the
middle; lastly, there is a small black speck on each side, behind the
third segment. This is the initial costume. Presently orange-red will
take the place of the pale amber. The tiny creature, which is
exceedingly fat, sticks to the leaf with its short legs and also with
its hind-quarters, which act as a lever and push the round belly
forwards. The motion reminds you of a cripple sitting in a bowl.
[Footnote 2: .959 inch.--_Translator's Note_.]
The grubs emerging from any one group of eggs at once begin to browse,
each beside the empty skin of its egg. Here, singly, they nibble and
dig themselves a little pit in the thickness of the leaf, while
sparing the cuticle of the opposite surface. This leaves a translucent
floor, a support which enables them to consume the walls of the
excavation without risking a fall.
Seeking for better pasture, they move lazily on. I see them scattered
at random; a few of them are grouped in the same trench; but I never
see them browsing economically abreast as Reaumur relates. There is no
order, no understanding between messmates, contemporaries though they
be and all sprung from the same row of eggs. Nor is any heed paid to
economy: the lily is so generous!
Meanwhile, the paunch swells and the intestine labours. Here we are! I
see the first bit of the overcoat evacuated. As is natural in extreme
infancy, it is liquid and there is not much of it. The scanty flow is
used all the same and is laid methodically, right at the far end of
the back. Let the little grub be. In less than a day, piece by piece,
it will have made itself a suit.
The artist is a master from the first attempt. If its baby-flannel is
so good to start with, what will the future ulster be, when the stuff,
brought to perfection, is of much better quality? Let us proceed; we
know what we want to know concerning the talents of this manufacturer
of excremental broadcloth.
What is the purpose of this nasty great-coat? Does the grub employ it
to keep itself cool, to protect itself against the attacks of the sun?
It is possible: a tender skin need not be afraid of blistering under
such a soothing poultice. Is it the grub's object to disgust its
enemies? This again is possible: who would venture to set tooth to
such a heap of filth? Or can it be simply a caprice of fashion, an
outlandish fancy? I will not say no. We have had the crinoline, that
senseless bulwark of steel hoops; we still have the extravagant
stove-pipe hat, which tries to mould our heads in its stiff sheath.
Let us be indulgent to the evacuator nor disparage his eccentric
wardrobe. We have eccentricities of our own.
To feel our way a little in this delicate question, we will question
the near kinsmen of the Lily-beetle. In my acre or two of pebbles I
have planted a bed of asparagus. The crop, from the culinary point of
view, will never repay me for my trouble: I am rewarded in another
fashion. On the scanty shoots which I allow to display themselves
freely in plumes of delicate green, two Crioceres abound in the
spring: the field species (_C. campestris_, LIN.) and the
twelve-spotted species (_C. duodecimpunctata_, LIN.). A splendid
windfall, far better than any bundle of asparagus.
The first has a tricolor costume which is not without merit. Blue
wing-cases, braided with white on the outer edge and each adorned with
three white dots; a red corselet, with a blue disk in the centre. Its
eggs are olive-green and cylindrical and, instead of lying flat,
grouped in short lines, after the manner of the lily-dweller's, occur
singly and stand on end on the leaves of the asparagus-plant, on the
twigs, on the flower-buds, more or less everywhere, without any fixed
order.
Though living in the open air on the leaves of its plant and thus
exposed to all the various perils that may threaten the Lily-grub, the
larva of the Field Crioceris knows nothing whatever of the art of
sheltering itself beneath a layer of ordure. It goes through life
naked and always perfectly clean.
It is of a bright greenish yellow, fairly fat behind and thinner in
front. Its principal organ of locomotion is the end of the intestine,
which protrudes, curves like a flexible finger, clasps the twig and
supports the creature while pushing it forward. The true legs, which
are short and placed too far in front with regard to the length of the
body, would find it very difficult by themselves to drag the heavy
mass that comes after. Their assistant, the anal finger, is remarkably
strong. With no support, the larva turns over, head downwards, and
remains suspended when shifting from one sprig to another. This
Jack-in-the-bowl is a rope-dancer, a consummate acrobat, performing
its evolutions amid the slender sprigs without fear of a fall.
Its attitude in repose is curious. The heavy stern rests on the two
hind-legs and especially on the crooked finger, the end of the
intestine. The fore-part is lifted in a graceful curve, the little
black head is raised and the creature looks rather like the crouching
Sphinx of antiquity. This pose is common at times of slumber and
blissful digestion in the sun.
An easy prey is this naked, plump, defenceless grub, snoozing in the
heat of a blazing day. Various Gnats, of humble size, but very likely
terribly treacherous, haunt the foliage of the asparagus. The larva of
the Crioceris, motionless in its sphinx-like attitude, does not appear
to be on its guard against them, even when they come buzzing above its
rump. Can they be as harmless as their peaceful frolics seem to
proclaim? It is extremely doubtful: the Fly rabble are not there
merely to imbibe the scanty exudations of the plant. Experts in
mischief, they have no doubt hastened hither with another object.
And, in truth, on the greater number of the Crioceris-larvae we find,
adhering firmly to the skin, certain white specks, very small and of a
china-white. Can these be the sowing of a bandit, the spawn of a
Midge?
I collect the grubs marked with these white specks and rear them in
captivity. A month later, about the middle of June, they shrivel,
wrinkle and turn brown. All that is left of them is a dry skin which
tears from end to end, half uncovering a Fly-pupa. A few days later,
the parasite emerges.
It is a small, greyish Fly, fiercely bristling with sparse hairs, half
the size of the House-fly, whom it resembles slightly. It belongs to
the Tachina group, who, in their larval form, so often inhabit the
bodies of caterpillars.
The white spots sprinkled over the larva of the Crioceris were the
eggs of the hateful Fly. The vermin born of those eggs have perforated
the victim's paunch. By subtle wounds, which cause little pain and are
almost immediately healed, they have penetrated the body, reaching the
humours in which the entrails are bathed. At first the larva invaded
is not aware of its danger; it continues to perform its rope-dancer's
gymnastics, to fill its belly and to take its siestas in the sun, as
though nothing serious had occurred.
Reared in a glass tube and often examined under the lens, my
parasite-ridden larvae betray no uneasiness. The fact is that the
Tachina's children display an infernal judgment in their first
actions. Until the moment when they are ready for the transformation,
their portion of game has to hold out, must be kept fresh and alive.
They therefore gorge themselves with the reserves intended for future
use, the fats, the savings which the Crioceris hoards in view of the
remodelling whence the perfect insect will emerge; they consume what
is not essential to the life of the moment and are very careful not to
touch the organs which are indispensable at the present time. If these
received a bite, the host would die and so would they. Towards the end
of their growth, prudence and discretion being no longer essential,
they make a complete clearance of the victim, leaving only the skin,
which will serve them for a shelter.
One satisfaction is vouchsafed me in these horrible orgies: I see that
the Tachina in her turn is subjected to severe reductions. How many
were there on the larva's back? Perhaps eight, ten or more. One Midge,
never more than one, comes out of the victim's skin, for the morsel is
too small to provide food for many. What has become of the others? Has
there been an internecine battle inside the poor wretch's body? Have
they eaten one another up, leaving only the strongest to survive, or
the one most favoured by the chances of the fight? Or has one of them,
earlier developed than the rest, found himself master of the
stronghold and have the others preferred to die outside rather than
enter a grub already occupied, where famine would be rife if the
messmates numbered even two? I am all for mutual extermination.
Kinsman's flesh or stranger's flesh must be all one to the fangs of
the vermin swarming in the Crioceris' belly.
Fierce though the competition is among these bandits, the Beetle's
race does not threaten to die out. I review the innumerable troop on
my asparagus-bed. A good half of them have Tachina-eggs plainly
visible as tiny white specks on their green skins. The blemished
larvae tell me of a paunch already or on the point of being invaded.
On the other hand, it is doubtful whether those which are unscathed
will all remain in that condition. The malefactor is incessantly
prowling around the green plumes, watching for a favourable
opportunity. Many larvae free from white spots to-day will show them
to-morrow or some other day, so long as the Fly's season lasts.
I estimate that the vast majority of the troop will end by being
infested. My rearing-experiments tell me much on this point. If I do
not make a careful selection when I am stocking my wire-gauze-covers,
if I go to work at random in picking the branches colonized with
larvae, I obtain very few adult Crioceres; nearly all of them are
resolved into a cloud of Midges.
If it were possible for us to wage war effectually upon an insect, I
should advise asparagus-growers to have recourse to the Tachina,
though I should cherish no illusions touching the results of the
expedient. The exclusive tastes of the insect auxiliary draw us into a
vicious circle: the remedy allays the evil, but the evil is
inseparable from the remedy. To rid ourselves of the ravages of the
asparagus-beds, we should need a great many Tachinae; and to obtain a
great many Tachinae we should first of all need a great many ravagers.
Nature's equilibrium balances things as a whole. Whenever Crioceres
abound, the Midges that reduce them arrive in numbers; when Crioceres
become rare, the Midges decrease, but are always ready to return in
masses and repress a surplus of the others during a return of
prosperity.
Under its thick mantle of ordure the grub of the Lily-beetle escapes
the troubles so fatal to its cousin of the asparagus. Strip it of its
overcoat: you will never find the terrible white specks upon its skin.
The method of preservation is most effective.
Would it not be possible to find a defensive system of equal value
without resorting to detestable filth? Yes, of course: the insect need
only house itself under a covering where there would be nothing to
fear from the Fly's eggs. This is what the Twelve-spotted Crioceris
does, occupying the same quarters as the Field Crioceris, from whom
she differs in size, being rather larger, and still more in her
costume, which is rusty red all over, with twelve black spots
distributed symmetrically on the wing-cases.
Her eggs, which are a deep olive-green and cylindrical, pointed at one
pole and squared off at the other, closely resemble those of the Field
Crioceris and, like these, usually stand up on the supporting surface,
to which they are fastened by the square end. It would be easy to
confuse the two if we had not the position which they occupy to guide
us. The Field Crioceris fastens her eggs to the leaves and the thin
sprays; the other plants them exclusively on the still green fruit of
the asparagus, globules the size of a pea.
The grubs have to open a tiny passage for themselves and to make their
own way into the fruit, of which they eat the pulp. Each globule
harbours one larva, no more, or the ration would be insufficient.
Often, however, I see two, three or four eggs on the same fruit. The
first grub hatched is the one favoured by luck. He becomes the owner
of the pill, an intolerant owner capable of wringing the neck of any
who should come and sit down at table beside him. Always and
everywhere this pitiless competition!
The grub of the Twelve-spotted Crioceris is a dull white, with an
interrupted black scarf on the first segment of the thorax. This
sedentary creature has none of the talents of the acrobat grazing on
the swaying foliage of the asparagus; it cannot take a grip with its
posterior, turned into a prehensile finger. What use would it have for
such a prerogative, loving repose as it does and destined to put on
fat in its cell, without roaming in quest of food? In the same group
each species has its own gifts, according to the kind of life that
awaits it.
It is not long before the occupied fruit falls to the ground. Day by
day, it loses its green colour as the pulp is consumed. It becomes, at
last, a pretty, diaphanous opal sphere, while the berries which have
not been injured ripen on the plant and acquire a rich scarlet hue.
When there is nothing left to eat inside the skin of its pill, the
grub makes a hole in it and goes underground. The Tachinae have spared
it. Its opal box, the hard rind of the berry, has ensured its safety
just as well as a filthy overcoat would have done and perhaps even
better.