OTHER LEAF-ROLLERS

The Life of the Weevil by Jean-Henri Fabre and Alexander Teixeira de Mattos, is part of the HackerNoon Books Series. You can jump to any chapter in this book here. OTHER LEAF-ROLLERS

Chapter IX. OTHER LEAF-ROLLERS

Is the insect’s trade determined by the nature of the tools of which it disposes, or, on the contrary, is it independent of them? Does the organic structure govern the instincts, or do the insect’s various aptitudes hark back to origins that cannot be explained merely by the details of its anatomy? We shall obtain an answer to these questions from two other leaf-rollers, the Apoderus of the Hazel (A. coryli, Lin.) and the Attelabus (A. curculionoides, Lin.), both of them eager rivals of the cigar-makers who work the poplar and the vine.

According to the Greek lexicon, the term Apoderus ought to mean ‘the flayed.’ Is this really what the author of the expression had in mind? My few books, the odd volumes of a village naturalist, do not enable me to reply. However, to me the word is explained by the insect’s colour.

The Apoderus is a skinless creature, displaying its naked and bleeding misery. Its colour is vermilion, as bright as sealing-wax. It is like a drop of arterial blood coagulated on the dark green of a leaf.

To this loud costume, rare among insects, are [141]added other, equally unusual characteristics. The Weevils are all microcephalous. This one exaggerates the absurd disproportion even further: she retains only the indispensable minimum of a head, as though she were trying to do without one altogether. The cranium in which her poor brain is lodged is a paltry, glittering, jet-black speck. In front of this speck is no beak, but a very short, wide snout; behind is an unsightly neck, which one might imagine to have been strangled in a halter.

Standing high on her legs, clumsy in her gait, she ambles step by step across her leaf, which she pierces with round windows. The material removed is her food. Faith, a strange creature: a reminiscence, maybe, of some ancient mould, cast aside by life’s progress!

Three Apoderi and no more figure in the European fauna. The best-known is that of the hazel. This is the one to whom I propose to devote my attention. I find her here, not on the hazel, her lawful domain, but on the common alder. This change in her activities deserves a brief investigation.

My district does not suit the hazel very well; the climate is unfavourable, being too hot and dry. On the high slopes of Mont Ventoux it grows sparsely; in the plain, except in the gardens where a few find a footing, they are no longer to be seen. In the absence of the fostering bush, [142]the insect, without becoming impossible, is at least extremely rare.

Long though I have been beating the brambles of my countryside over an umbrella held upside down, here is our Apoderus for the first time. For three springs in succession I see the red Weevil on the alder and observe her work. One tree, one alone and always the same, in the osier-beds of the Aygues provides me with this leaf-roller, whom I now for the first time see alive. The other alders round about have not a trace of her, though they are only a few yards distant. There is here, on this privileged tree, a small, accidental colony, a settlement of foreigners, who are becoming acclimatized before extending their domain.

How did they come here? Undoubtedly brought by the torrent. The geographers call the Aygues a water-course. As an eye-witness, I should call it, more accurately, a pebble-course. Understand me: I do not mean that the dry pebbles flow down it of themselves; the low gradient does not permit of such an avalanche. But only let it rain; and they will stream fast enough. Then I can hear the roar of the grinding stones from my house, a mile and a quarter distant.

During the greater part of the year, the Aygues is a broad expanse of white pebbles; of the torrent naught remains but the bed, a furrow of enormous width, comparable with that of its mighty neighbour, the Rhone. Let the rain fall persistently, [143]let the snows melt on the slopes of the Alps; and the thirsty furrow fills for a few days: roaring, it overflows to a great distance and turbulently shifts its shoals of pebbles. Return a week later. The roar of the flood is succeeded by silence. The terrible waters have disappeared, leaving on the banks, as the trace of their brief passage, wretched muddy puddles soon absorbed by the sun.

These sudden freshets bring a thousand live gleanings swept off the flanks of the mountains. The dry bed of the Aygues is a most interesting botanical garden. There you may gather many vegetable species brought down from the higher levels, some temporary, disappearing without offspring in a single season, others persisting and adapting themselves to the new climate. They come from far away, from the heights, these exiles; to pluck this one or that in its true environment you would have to climb Mont Ventoux, pass beyond the zone of the beeches and reach the altitude where trees cannot grow.

Alien zoology in its turn is represented in the osier-beds, whose calm is disturbed only during unusually prolonged floods. My attention is attracted especially by the land-mollusc, that champion stay-at-home. In stormy weather, when the thunder growls—lou tambour di cacalauso, as the Provençal calls it—the most that the Snail permits himself in the matter of moving about is to issue from his stronghold, some crevice in the rocks, [144]and to browse before his door upon the grasses, mosses and lichens made tender by the flood. It takes a cataclysm to make that one travel!

The wild freshets of the Aygues succeed in doing so. They bring into my part of the world and deposit in the osier-thickets the largest of our Snails, Helix pomatia, the glory of Burgundy.1 Rolled down the grassy mountain-slopes by the showers, the exile defies immersion within the water-tight cover of his chalky operculum; he endures the jolting, thanks to his strong shell. He travels by stages, from one osier-bed to another. He descends as far even as the Rhone and colonizes the Île des Rats and the Île du Colombier opposite the mouth of the Aygues.

Whence does he come, this enforced emigrant, whom one would vainly seek elsewhere in the land of the olive? He loves a moderate temperature, green turf, cool shades. His place of origin is certainly not here, but far away on the rounded heights of the lower, outermost Alps. The highlander’s exile none the less seems pleasant. The big Snail does quite well in the marshy scrub on the banks of the torrent.

Neither is the Apoderus a native. She is a castaway, hailing from the hazel-clad heights. She has made the voyage in a little boat, that is to say, in the leafy cockle-shell in which the grub is born. The vessel was tightly closed, which [145]made the passage possible. Running ashore at some point on the bank in the height of summer, the insect perforated its cell and, not finding its favourite tree, established itself upon the alder. There it founded a family, remaining faithful to the same tree for the three years during which I had to do with it. It is probable, for that matter, that the origin of the settlement dates farther back.

The history of this stranger interests me. The primordial conditions of her life—climate and food—are changed. Her ancestors lived under a temperate sky; they grazed on the leaf of the hazel-bush; they manufactured cylinders out of piece-goods made familiar by the constant practice of past generations. But the wanderer is living under a torrid sky; she grazes on the alder-leaf, whose flavour and nutritive properties must differ from those of the family diet; she works at an unknown piece, though it is not unlike the normal piece in shape and size. What changes has this disturbance of its diet and climate effected in the insect’s characteristics?

Absolutely none. In vain I pass the magnifying-glass over the exploiter of the alder and over the exploiter of the hazel-bush, of whom the latter has reached me from the heart of the Corrèze by post. I see not the least difference between the two, even in the smallest details. Can the method of industry have been modified? Without seeing [146]the work done with a hazel-leaf, I boldly assert that it is similar to that obtained with an alder-leaf.

Change the food and the climate, change the materials to be worked: if it can adapt itself to the new conditions imposed upon it, the insect persists, immutable in its craft, habits and organization; if it cannot, it dies. To be as one was or not to be: that is what the castaway of the torrent, like so many others, tells us.

Let us watch her at work on the alder and we shall know how she labours on the hazel-bush. The Apoderus does not know the method of the Rhynchites, who, to kill the elasticity of the leaf to be rolled, makes a deep puncture in the stalk. The red leaf-roller has a special modus operandi, in no way related to that of the puncture.

Can this change of method be due to the absence of the rostrum, of the fine awl capable of being driven into the narrow leaf-stalk? It is possible, but not certain, for the snout, an excellent pair of shears, could cut half through the leaf-stalk at a bite and obtain an equivalent result. I prefer to see in the novel procedure one of those methods which are the separate property of every specialist. We must never judge of the work by the tool employed. The insect is an adept at using any sort of implement, even though defective.

The fact is that with her mandibles the Apoderus slashes the alder-leaf cross-wise, at some distance [147]from the base. The whole leaf is cut clean through, including even the central vein. The only part left intact is the extreme edge, from which the large severed area hangs withering.

This area, the greater part of the leaf, is then folded in two along the principal vein, with the green or upper surface inside; then, starting from the tip, the folded sheet is rolled into a cylinder. The orifice above is closed with that part of the border which the cut has left untouched; the orifice below is closed with the edges of the leaf tucked inwards.

The pretty little barrel hangs perpendicularly, swaying to the least breeze. It is hooped by the median vein, which projects at the upper end. Between the second and third pages, as it were, of the double sheet, near the middle of the spiral, is the egg, resin-red and, this time, single.

The few cylinders which I have been able to examine afford me no circumstantial details touching the development of their inmate. The most interesting fact which I learn from them is that the grub, when it has attained its full growth, does not go underground as the others do. It remains in its barrel, which the wind soon shakes down into the grass. That half-decayed shelter would be very unsafe in bad weather. The red Weevil knows this. She hastens to assume her adult form, to don her scarlet cloak; and by the beginning of summer she abandons her cylinder, [148]now a mere wreck. She will find a better refuge under the loose strips of old bark.

Attelabus curculionoides is no less expert in the art of making a keg out of a leaf. There is one curious point of resemblance: the new cooper is red, like the other, or, more accurately speaking, crimson. The rostrum is very short and expanded into a snout. Here the likeness ceases. Our first friend is rather fine-drawn and loose-limbed; the second is a thickset, round, dumpy Weevil. We are quite surprised by her work, which seems incompatible with the worker’s awkward, clumsy build.

And she does not work a docile stuff either: she rolls ilex-leaves, young ones, it is true, not yet too stiff. It is a tough material all the same, difficult to bend and slow in fading. Of the four leaf-rollers of my acquaintance, the smallest, the Attelabus, has the hardest lot; nevertheless, it is she, the dwarf, such a bungler in appearance, who by dint of patience builds the prettiest house.

At other times she exploits the common oak, the English oak, whose leaves are broader and more deeply indented than those of the ilex, or holm-oak. On the spring shoots she selects the topmost leaves, of average size and medium consistency. If the position suit her, five, six or more little kegs will be dangling from the same twig.

Whether it settle on the holm-oak or on the common oak, the insect begins by incising the [149]leaf, at some distance from the base, to the right and left of the median vein, while respecting the vein itself, which will provide a solid attachment. Then the Apoderus’ method is repeated: the leaf, rendered more tractable by the two incisions, is folded lengthwise, with the upper surface inside. All these leaf-rollers, cigar-makers and coopers alike, know how to overcome the resilience of a leaf by means of punctures or incisions; all are thoroughly versed in that principle of statics according to which the surface whose elasticity is the greater will be found on the convex aspect of the curve.

Between the two sheets which touch, the egg is laid, again one egg. Then the double leaf is rolled from the tip to the attachment. The indentations, the serrations of the last fold are sealed down by the patient pressure of the snout; the two mouths of the cylinder are closed by turning the edges in. It is finished. The barrel is completed, about two-fifths of an inch long and hooped at its fixed end by the median vein. It is small but strong and not devoid of elegance.

The thick-set cooper has her merits, which I should like to elucidate more fully by watching her at work. What I have contrived to see in the open, in the actual workshop, amounts to little more than nothing. Many a time do I surprise the Weevil on her cask, motionless, with her snout against the staves. What is she doing [150]there? She is sleeping in the sunlight; she is waiting for the last layer of the work to acquire a firm hold under prolonged pressure. If I examine her too closely, she at once gathers her legs under her belly and lets herself fall.

Since my visits tell me hardly anything, I try to rear the insect in domesticity. The Attelabus lends herself very well to the attempt: she works under my bell-jars as zealously as on her oak. What I now learn deprives me of all hope of following the details of the leaf-rolling process: the Attelabus is one of those who work at night.

Late in the evening, about nine or ten o’clock, she gives the cuts of the scissors that slash the leaf; next morning the keg is finished. Seen by the uncertain light of a lamp and at untimely hours, hours rightly claimed by sleep, the worker’s delicate technique would escape me. We will give up the idea.

There is a reason for these nocturnal habits. I think I see what it is. The leaf of the oak, especially of the holm-oak, is much harder to bend than the leaf of the alder, the poplar or the vine. If rolled in the daytime, under the burning rays of the sun, it would add to the difficulties arising from indifferent flexibility those due to incipient dryness. On the other hand, when visited by the dew, in the coolness of the night, it will remain pliable; it will yield adequately to the efforts of the roller; and the barrel will [151]be ready when the sun comes, with its blazing heat, to steady the shape of the still moist fabric.

However different one from the other, the four leaf-rollers have shown us that the individual craft is not a matter of organic structure, that the tool does not determine the nature of the work. Whether endowed with a rostrum or a snout, whether long-legged or slow, slender or thickset, perforators or cutters-out, they all four achieve the same result, the cylinder that acts as a shelter and a larder for the grub.

They tell us that instinct has its origin elsewhere than in the organs. It goes farther back; it is inscribed in the primeval code of life. Far from being dependent on the tools, it commands them and is able to employ them as it finds them, with the same skill, for one task here and for another there.

The little cooper of the oak-tree has not finished with her revelations. Having observed her pretty frequently, I know how fastidious she is of the quality of her victuals. If they be dry, she refuses them absolutely, even though it means dying of starvation. She wants them tender, pickled in moisture, softened by incipient decay, even seasoned with a touch of mildew. I prepare them to her liking by keeping them in a jar on a bed of moist sand.

Thus treated, the grub hatched in June soon increases in size. Two months are enough to [152]turn it into a handsome orange-yellow larva, which, when its cell is broken open, suddenly, with the violence of a spring released, straightens its curved body and tosses about. Observe its slender form, much less stout than that of the other Weevils in general. This is the only instance in which lack of corpulence in the larva denotes an adult of an exceptional class. I shall say no more on the subject of the grub: its description would be of no particular interest.

The matter deserves looking into more closely. It is the end of September; we have been suffering from an extraordinarily hot and dry summer. The dog-days seem determined to last for ever. The forests are ablaze in the Ardèche, the Bordeaux and the Roussillon districts; whole villages have been burnt down on the slopes of the Alps; in front of my door, a careless passer-by, throwing away a match, sets fire to the neighbouring meadows. You cannot call it a summer: it is a conflagration.

What can the Attelabus be doing in such disastrous weather? She is thriving comfortably in my jars, which keep her victuals soft for her; but, at the foot of her oak, amid the undergrowth shrivelled as though by the breath of a furnace, on the calcined earth, what becomes of the poor thing? Let us go and see.

Beneath the oaks which she was exploiting in June, I succeed in finding, among the dead leaves, [153]a dozen of her little barrels. They have retained their green colour, so suddenly did the desiccation seize them. They crack and crumble into dust under the pressure of the fingers.

I open a barrel. In the middle is the grub, looking fit enough, but how small! It is hardly larger than when it left the egg. Is it dead or alive, this yellow atom? Its immobility proclaims it to be dead; its unfaded colour proclaims it to be alive. I break open a second barrel, a third. In the middle there is always a yellow grub, motionless and quite small, as though newly-born. We will stop at this and keep the rest of my collection for an experiment that occurs to my mind.

With their mummy-like immobility, are the grubs really dead? No; for, if I prick them with the point of a needle, they twitch immediately. Their condition is merely one of arrested development. In their freshly-rolled sheath, still hanging from the tree and receiving a little sap, they found the food necessary for their early growth; then the barrel fell to the ground, where it soon dried up.

Then, disdaining its hard provender, the grub ceased to eat and grow. Who sleeps dines, so the proverb says; and it is waiting in a state of torpor for the rain to soften its bread.

This rain, for which man and beast have been sighing for four months past, I have it in my power [154]to realize, at least to the limits of a Weevil’s requirements. I float the rest of the dry barrels in water. When they are thoroughly soaked, I transfer them into a glass tube, closed at either end with a plug of wet cotton-wool which will keep the atmosphere moist.

The result of my stratagems deserves mention. The sleepers awake, eat the inside of the softened loaf, and make up so well for lost time that in a few weeks they are as large as those which have not suffered any interruption in my jars half full of moist earth.

This knack of suspending life for months at a time, when the provisions have lost the requisite tenderness, is not repeated in the other leaf-rollers. At the end of August, three months after the hatching, there is nothing left alive in the cigars of the vine which have been allowed to dry. Death is even swifter in the withered cigars of the poplar. As for the cylinders of the alder, in the absence of a sufficient number of leaves, I was not able to estimate their inhabitants’ powers of endurance.

Of the four leaf-rollers, the one most threatened by drought is that of the oak. Her barrel falls and lies on a soil which is extremely arid except at times of rain; moreover, because of its small dimensions, it dries right through at the first touch of the sun.

The ground is equally dry in the vineyard; but there is shade under the branches, and the [155]generous cigar is thick enough to retain in its central part, far better than the slender barrel does, a little of the moisture indispensable to the grub. In respect of prolonged abstinence, the Vine-weevil cannot be compared with the barrel-maker; still less can the Poplar-weevil. For this last, more often than otherwise, there is no danger from drought, despite the smallness of the cylinder, a sorry rat’s-tail. This roll usually falls by the side of a ditch, on the moist soil of the meadows. The exploiter of the alder is hardly in danger either: at the foot of her tree, a lover of the trickling brooks, she finds the coolness needed to keep her food-cylinder in good condition. But, when she exploits the hazel-bush, I do not know what conditions help her out of her difficulty.

Lately the newspapers, which noisily echo every piece of absurdity, have been making a certain fuss about the gastric feats of a few poor devils who, to earn their bread, have fasted for thirty or forty days. As in most stunts, admirers were found, ready to encourage those wretched competitions.

Now here is something far better, ye snobbish upholders of abstinence! A trivial beastie, not celebrated by the newspapers, a grub born the day before yesterday, takes a few mouthfuls; then, finding its victuals too dry, it eats no more for four months or longer. And this is not the result of sickly languor: the creature fasts in spite of the [156]extreme appetite of youth, when, more than ever, the stomach demands a copious diet. The Rotifer,2 which for a whole season lies lifeless and desiccated in the mosses of its home, begins to whirl round again when placed in a drop of water. The grub of the Attelabus, lying near to death for four or five months, recovers its liveliness and eats like a glutton if I moisten its bread for it. What can life be, capable of such intermissions?

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