THE VINE-WEEVIL
In the spring, while the poplar-leaves are being worked into cylinders,
another Rhynchites, who is likewise magnificently attired, is making
cigars out of vine-leaves. She is a little bigger, of a metallic
lustre, a golden green that changes to blue. Were she only larger, the
resplendent Vine-weevil would occupy a very respectable place among the
gems of entomology.
To attract our eyes, she has something better than her brilliancy: she
has her industry, which has earned her the hatred of the vine-grower,
jealous of his property. The peasant knows her: he even calls her by a
special name, an honour rarely bestowed in the world of the smaller
creatures.
The rural vocabulary is rich in names of plants, but very poor in names
of insects. A couple of dozen words, inextricably confused because of
their general character, represent the whole list of insect names in
our Provençal idiom, expressive and fertile though this idiom be when
it refers to the vegetable world and even, at times, to a sorry weed
which one would think was known to the botanist only.
The man of the soil is interested above all things in the plant, the
great foster-mother; all else leaves him indifferent. Splendid
adornment, curious habits, marvels of instinct: all these make no
appeal to him. But to touch his vine, to eat other people’s grass: what
a heinous crime! Quick, a name, a badge of infamy, to hang round the
malefactor’s neck!
This time the Provençal peasant has taken the trouble to invent a
special term: he calls the cigar-roller the Bécaru. Here the scientific
name and the rural name are in complete agreement. Rhynchites and
Bécaru are exact equivalents: both allude to the insect’s long beak.
But how much more correct is the vine-grower’s term, in its lucid
simplicity, than the scientific name, set forth in full, with its
imperative complement relating to the species! I rack my brain in vain
to guess the reason why the cigar-roller of the vine was called the
Rhynchites of the Birch (R. betuleti, Fab.).
If there be in fact a Weevil that exploits the birch-tree, it is
certainly not the same as that of the vineyards: the two leaves to be
rolled are too dissimilar in shape and size to suit the same worker.
Recorders of descriptions, you who, under the scrupulous eye of the
magnifying-glass, specify the shapes and establish the identity of the
animal species, before you give names and surnames to your impaled
insects, pray, pray inquire a little into their manner of life. By so
doing, you will see things more clearly, you will avoid much detestable
nonsense, and you will spare the novice such doubts as those which
obsess him when he finds himself obliged to label a Weevil inhabiting
the vine-branches as a Rhynchites of the Birch. We are ready to excuse
cacophonous syllables and grating consonants; but we reject with
exasperation a name that misrepresents the facts.
In her work the Vine-weevil pursues the same method as the
Poplar-weevil. The leaf is first pricked with the rostrum at a point on
the stalk, which checks the flow of the sap and makes the edges of the
faded leaf pliable. The rolling begins at the angle of one of the lower
lobes, with the smooth, green upper surface inside and the downy,
strongly-veined lower surface outside.
But the great size of the leaf and its deeply indented outline hardly
ever allow of regular work from one end of the leaf to the other. Over
and over again, sudden folds occur and alter the direction of the
rolling, leaving now the green and now the downy surface outside,
without any appreciable design, as though by chance. The poplar-leaf,
with its simple form and its moderate size, yields an elegant cylinder;
the vine-leaf, with its cumbersome width and complicated outline,
produces a shapeless cigar, an untidy bundle.
This is not due to defective talents, but to the difficulty of
manipulating and controlling a leaf of this kind. The mechanical
method, indeed, is the same as that practised on the poplar-leaf. With
three legs here and three legs there on the edges of the fold, the
Bécaru obtains a purchase on one side and tugs and strains on the
other.
Like her rival cigar-maker, she works backwards, keeping her eyes upon
the part which, folded that moment and still unset, may require
immediate touching up. The product is thus watched until it gives proof
of its stability.
Like the other, she too seals the denticulations of the final layer by
pressing them with her rostrum. Here there is no sticky secretion
oozing from the edges of the leaf, but there is a downy fluff whose
fibres get entangled and cause adhesion. On the whole, therefore, the
method employed by the two Rhynchites is the same.
Nor do their domestic habits differ. While the mother is patiently
rolling her cylinder, the father remains close at hand, on the same
leaf. He looks on. Next, he comes running along in a hurry, takes his
stand in the crease and kindly lends the assistance of his
grappling-irons. But he again is not a very diligent helper. His brief
collaboration is a pretext to tease the worker and achieve his ends by
sheer persistence.
He retires satisfied. Let us watch him. Before the roll is finished, we
shall see him return many times, inspired by the same intentions, which
are rarely scorned. I need not insist further on these pairings, which
are repeated indefinitely and run counter to the classic data on one of
the nicest points of insect physiology. To impress the seal of life
upon the hundreds of eggs of the mother Bombyx, [43] or the thirty
thousand or more of the mother Bee, the father exerts only one direct
intervention. The Weevil claims the privilege of intervening for almost
every egg. I leave the curious problem to the experts.
Let us unroll a recently-made cigar. The eggs, fine, amber-coloured
beads, are scattered, one by one, at very different depths in the
spiral. As a rule, I find several, from five to eight. The multiplicity
of fellow-feasters, in both the rolled poplar-leaf and the rolled
vine-leaf, bears witness to extreme frugality.
The two leaf-rollers are quickly hatched: the grub is born in five or
six days’ time. Then the observer begins to be faced with the same
difficulties that beset a prentice hand in the rearing of larvæ; and
these difficulties are all the more exasperating in that there was
nothing to predict them. The course to be followed here seems indeed so
very simple.
Since the rolled leaves are at the same time board and lodging, we have
but to pick them, from the vine and the poplar respectively, and to
place them in the glass jars, whence we can take them at such times as
we consider suitable. What used to be effected in the open air, amid
the disturbances of the atmosphere, will be effected all the better in
the peaceful shelter of the glass. There can be no doubt, therefore, of
an easy success.
But what is this? From time to time I unroll a few cigars to ascertain
the state of their contents. What I see fills me with anxiety for the
fate of my baby-farm. The young larvæ are very far from thriving. I
find some of them languishing and emaciated, shrivelling into a
wrinkled ball; I find some of them dead. Vainly I possess myself in
patience: the weeks go by and not one of my grubs grows or gives a sign
of energy. From day to day my two colonies dwindle until they consist
wholly of dying larvæ. When July comes, there is not a living thing
left in my glass jars.
All have died. And of what? Of starvation, yes, of starvation in a
well-stored granary. This is evident from the small amount of food
consumed. The cylinders are almost untouched; at most I perceive in the
midst of their layers a few scratches, the traces of a scornful tooth.
Probably the food was too dry, had been rendered uneatable by
desiccation.
Under natural conditions, while the burning heat of the sun hardened
the leaves by day, the mists and the dew softened them at night. Thus,
in the heart of the spiral layers, a column of soft crumb is preserved,
a necessity for the tender nurselings. A sojourn in the uniformly dry
atmosphere of the jars has, on the other hand, turned the roll into a
hard, stale crust which the grubs refused to touch. The failure is due
to that.
A year later, I begin again, this time more cautiously. The rolled
leaves, I said to myself, remain hanging for some days on the vine or
the poplar. The perforation of the leaf-stalk has not completely
severed the ducts conveying the sap; a scanty flow still persists and
for some time maintains a certain flexibility in the leaf, especially
in the centre of the spiral, which is not exposed to the action of the
sun. Consequently the new-born grub has fresh provisions within reach
of its mandibles. It waxes big and strong and acquires a stomach able
to satisfy itself with less tender food.
Meantime, from day to day, the roll turns brown and dry. If it remained
indefinitely hanging on the bough and if, as often happens, there were
a lack of moisture at nights, it would dry up completely and its
inmates would perish as they did in my glass jars. But, sooner or
later, the wind shakes them off and they drop to the ground.
Their fall is the salvation of the grub, which is still very far from
full-grown. At the foot of the poplar, under the grass of the meadow
subject to frequent irrigation, the soil is always damp; at the foot of
the vine-stock, the earth, overshadowed by the branches, fairly well
retains the moisture of the last showers. Lying in the wet and
sheltered from the direct onslaughts of the sun, the Rhynchites’
victuals remain as soft as need be.
Thus I argued, meditating a fresh experiment; and the facts confirmed
the accuracy of my forecast. This time all goes well. Rather than the
green rolls of recent manufacture, I gather the brown cigars which are
due to fall to the ground. The larvæ in these latter, being older, are
less difficult to rear. Lastly, my harvest is installed in glass jars
as before, but on a bed of moist sand. With this and this alone I
achieve complete success.
Despite the mildew which this time invades the heaped cigars and seems
bound to jeopardize everything, the larvæ thrive and grow without
hindrance. The decay which I distrusted so much in the beginning, when
I kept my crops dry to avoid it, this decay suits them. I see them
taking big mouthfuls of decomposing shreds, the tainted remains of
leaves that have almost turned to mould.
I am no longer surprised that in my first experiments my nurselings
allowed themselves to die of hunger. Obeying a mistaken idea of
hygiene, I took pains to keep the rations in good condition, in an
atmosphere free from mustiness. I ought, on the contrary, to have
allowed fermentation to do its work, softening the tough tissues and
enhancing their flavour.
Six weeks later, in the middle of June, the oldest rolls are
dilapidated hovels, retaining scarcely a trace of their cylindrical
form save the outer layer, a protecting roof. Let us open one of these
ruins. Inside, there is absolute wreck, a mixture of shapeless remnants
and black granules, like fine gunpowder; outside, a crumbling envelope,
pierced here and there with holes. These openings tell me that the
inhabitants have departed and made their way underground.
I find them, in fact, in the layers of moist sand with which the jars
are provided. Pushing and heaving with their backs, they have each dug
themselves a round hollow, taking up the least possible room, in which
the grub, rolled into a bunch, makes ready for its new life.
Though formed of sandy particles, the wall of the cell does not
threaten to collapse. Before lapsing into the sleep of the
transformation, the recluse has deemed it prudent to strengthen its
house. With a little care, I am able to detach the dwelling in the form
of a little ball the size of a pea.
I then discover that the materials are cemented by means of a gummy
produce which, liquid at the moment of its emission, has penetrated to
a sufficient depth and welded the sandy grains into a wall of a certain
thickness. This product, which is colourless and not very plentiful,
leaves me in doubt as to its origin. It certainly does not come from
glands similar to the silk-tubes of the caterpillars; the Weevil-grub
possesses nothing of that kind. It is, therefore, a contribution from
the digestive canal, presented through either the entrance or the
exit-door. Which of the two?
Without completely solving the question of this cement, another Weevil
supplies a fairly probable answer. This is Brachycerus algirus, Fab.,
an ugly, unwieldy insect, covered with little warts each ending in a
claw-like horn. It is soot-black and almost always soiled with earth
when you meet it in spring. This dusty garb denotes a tunneller.
The Brachycerus, in fact, haunts the subsoil, hunting for garlic, the
exclusive food of her larva. In my modest kitchen-garden, garlic, dear
to the Provence folk, has its special corner. At the time when we
gather it, in July, most of the heads give me a magnificent grub, fat
as butter, which has dug itself a large hollow in one of the cloves,
only one, without touching the rest. This is the grub of the
Brachycerus, which discovered the aioli of the Provençal cooks long
before they did.
Raw garlic, Raspail [44] used to say, is the camphor of the poor. The
camphor possibly, but not the bread. This paradox becomes a reality in
the case of our grub, which is so much in love with this powerful
condiment that it will not eat anything else its whole life long. How,
with this fiery diet, does it put on such fine layers of fat? That is
its secret; and there is room for every sort of taste in this world of
ours.
After eating its clove, this lover of garlic dives deeper into the
soil, fearing perhaps the lifting of the bulbs, the time for which will
soon arrive. It foresees the annoyance which the market-gardener would
cause it; and it goes below, far from the natal plant.
I have reared a dozen in a jar half full of sand. Some have established
themselves right against the wall, which enables me to obtain a vague
idea of how things happen in the underground cell. The builder is bent
into a bow which now and again closes and forms a circle. I then seem
to see it collecting, with the tips of its mandibles, as the Larini do,
a sticky drop which forms at its hinder end. With this it soaks the
sandy wall and smears the glass, on which the stuff hardens in cloudy
streaks, white and pale-yellow.
On the whole, the appearance of the cement employed and the little that
I can see of the grub’s proceedings incline me to believe that the
Brachycerus strengthening its cabin uses the same method as the Larinus
building its thatched hut. The Brachycerus also knows the whimsical
secret of turning the intestine into a factory of hydraulic cement. The
sandy agglomerate thus obtained forms a fairly solid shell, in which
the insect, which reaches the adult stage in August, remains until the
garlic season is at hand.
This method may well be general among the various Weevils that, in the
larval, nymphal or adult state, spend part of the year tucked away in
an underground shell. The leaf-rollers, notably the Rhynchites of the
poplar and the vine, sparing though they be in the use of their cement,
no doubt have a store of it in their intestine, for it would be
difficult for them to find anything better. Let us, however, leave a
door open to doubt and continue.
For the first time, at the end of August, four months after the rolling
of the cigars, I take the Poplar-weevil in her adult form out of her
shell. I disinter her in all her gleaming gold and copper; but the
beauty, if I had left her undisturbed, would have slept in her
subterranean fortress till the young leaves sprouted on her tree, in
April.
I disinter others, soft and quite white, whose limp wing-cases open to
allow the crumpled wings to spread. The most advanced of these pale
sleepers boast, by way of a startling contrast, a deep-black rostrum
with violet gleams. The Sacred Beetle, in the early days of his final
form, begins by hardening and colouring his implements of labour: the
toothed arm-pieces and the clypeus with its semi-circular notching. The
Weevil likewise in the first place hardens and colours her drill. These
industrious workers interest me with their preparations. Barely has the
rest of the body set and crystallized before the tools of its future
work acquire exceptional strength, which they owe to an early and
long-protracted tempering.
From the broken shells I also take nymphs and larvæ. The latter
apparently will not pass beyond the first stage this year. What is the
use of hurrying? The larva, no less than the adult and perhaps more so,
is given to slumbering through the severities of the winter. When the
poplar unfurls its sticky buds and the Cricket on the greensward
strikes up the first bars of his melody, they will be ready, one and
all: the forward and backward alike; faithful to the call of spring,
all will come forth from the ground, eager to climb the kindly tree and
to renew the leaf-rollers’ festival in the sunlight.
In its pebbly, parching soil, on which the food-cylinders dry up so
quickly, the Vine-weevil lags behind, exposed as she is to periods of
unemployment due to the absence of properly softened food. It is in
September and October that I obtain the first adults, splendid gems,
enclosed, until spring, in their casket, the underground shell. At this
season there is an abundance of buried nymphs and larvæ. Many of the
grubs even have not yet left their cylinders; but, to judge by their
size, they will hardly linger much longer. At the first frosts, all
will become torpid and postpone their further development until the end
of the winter.