THE BOTANICAL INSTINCT

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. THE BOTANICAL INSTINCT

Chapter IV. THE BOTANICAL INSTINCT

Maternity, when it takes thought for the future, is the most fertile prompter of instinct. To the maternity that prepares board and lodging for the family we owe the wonderful achievements of the Dung-beetles and of the Wasps and Bees. The moment the mother confines herself to laying eggs and becomes a mere germ-factory, the industrial talents disappear as useless.

That bravely-plumed fine lady, the Pine Cockchafer, digs the sandy soil with the tip of her abdomen and buries herself in it laboriously right up to her head. Then a bundle of eggs is laid at the bottom of the excavation; and that is all, once the pit has been filled by means of a casual sweeping.

Constantly ridden by her male during the four weeks of July, the mother Capricorn explores the trunk of the oak at random; she slips her retractable oviscapt, here, there and everywhere, under the scales of the cracked bark, probing, feeling, choosing the propitious spots. Each time an egg is laid, almost without protection. This done, she has no further anxiety.[59]

The grub of Cetonia floricola, breaking its shell, some time in August, in the depths of the leaf-mould, goes to feed on the flowers and there idly slumbers; then, an adult Rose-chafer, she returns to the heap of rotten leaves, enters it and sows her eggs in the hottest places, those where fermentation rages most fiercely. Let us not ask anything further from her: her talents end with this.

So it is, in the vast majority of cases, with the other insects, weak or powerful, lowly or splendid. They all know where the eggs must be established, but they are profoundly indifferent to what will follow. It is for the grub to muddle through by its own methods. The Pine Cockchafer’s larva dives farther into the sand, seeking for tender rootlets softened by incipient decay. The Capricorn’s, continuing to drag the shell of its egg behind it, nibbles the uneatable for its first mouthful, making flour of the dead bark and sinking a shaft that leads it to the wood, on which it feeds for the next three years. The Cetonia’s, born in a heap of decomposed vegetable matter, has its food ready to its mouth, without seeking.

With such primitive habits as these, which emancipate the family at birth, without the least previous training, how far removed are we from the maternal tenderness of the Copris,1 the Necrophorus,2 [60]the Sphex3 and so many others! Apart from these privileged tribes, there is nothing very striking to be noted. It is enough to fill with despair the observer in search of facts really worth recording.

The children, it is true, often make up to us for their untalented mothers. Their ingenuity is sometimes amazing, from the time when they are hatched. Witness our Larini. What can the mother do? Nothing but bury the eggs in the blossoms of the thistles. But what a singular industry on the part of the grub which builds itself a thatched hut, upholsters itself a cabin, cards itself a mattress of chopped hairs, makes itself a defensive pitcher, a donjon-keep, with the shellac prepared by its intestine!

When the transformation is accomplished, what perspicacity on the part of the inexperienced insect, when it abandons its cosy home to seek a refuge under the rude shelter of the stones, foreseeing the winter which will ruin the natal villa! We possess the almanac of the past, telling us of the almanac of the future. The insect, with no records of the vicissitudes of the seasons; the insect, born in the dog-days, in the blazing heat of summer: the insect feels instinctively that this [61]period of solar intoxication will not last; it knows, though it has never seen it happen, that its house is doomed soon to collapse; and it makes off before the roof falls in.

For a Weevil, this is fine, magnificent. We might well envy the creature’s wisdom in being thus awake to the calamities of the future.

However devoid of industry she may be, the least-gifted mother none the less submits an insoluble problem for our consideration. What is it that leads her to lay her eggs at spots where the larvæ will find food to their liking?

The Pieris4 goes to the cabbage, in which she has no personal interest. The plant, compressed into a head, has not yet flowered. Besides, its modest yellow blossoms have no greater attraction for the Butterfly than an infinity of other flowers distributed broadcast. The Vanessa5 goes to the nettle, on which her caterpillars will feast, but on which the adult insect finds nothing to suck.

When, in the summer gloaming, the Pine Cockchafer has long been whirling in the nuptial ballet around her favourite tree, she refreshes herself after her fatigue by nibbling a few pine-needles; then, with impetuous flight, she goes in search of [62]some bare, sandy tract where the grass-roots lie decaying. Here, as often as not, there is no resinous aroma, there are no more pine-trees, the delight of the plumed beauty; and it is in this place, where nothing appeals to her own needs, that the mother, half-buried in the ground, will lay her egg.

That ardent lover of roses and hawthorn-blossom, the Golden Cetonia, leaves the luxury of the flowers, to burrow in the shame of putrescence. She repairs to the compost-heap, but is certainly not tempted by any dish to her taste. She cannot sip honey there nor intoxicate herself with perfumed essences. Another reason draws her to this corruption.

At first sight it would seem as if these strange instincts might be explained by the larva’s diet, of which the adult would retain a lively recollection. The caterpillar of the Pieris fed on cabbage-leaves; the caterpillar of the Vanessa fed on nettle-leaves; and each of the two Butterflies, endowed with a faithful memory, exploits the plant which has no attraction for her now, but which was a treat for her in her infancy.

In the same way, the Cetonia dives into the heap of leaf-mould because she remembers the feasts of former days, when she was a grub in the midst of the fermenting vegetable matter; and the Pine Cockchafer seeks the sandy tracts covered with lean tufts of grass, because she remembers [63]her youthful revels underground amid the decaying rootlets.

Such a memory would be almost admissible if the adult’s diet were the same as the larva’s. We can more or less understand the Dung-beetle, who, herself feeding upon animal droppings, makes them into canned provisions for her family. The diet of maturity and that of infancy are linked as though each were a reminiscence of the other. Uniformity offers a very simple solution of the food-problem.

But what shall we say of the Cetonia passing from the flowers to the sordid refuse of the decayed leaves? Above all, what shall we say of the Hunting Wasps? These fill their own crops with honey and feed their youngsters on prey!

By what inconceivable inspiration does the Cerceris6 leave the refreshment-bar of the blossoms, dripping with nectar, to go a-hunting and to slay the Weevil, the game destined for her offspring? How are we to explain the Sphex, who, having refreshed herself at the sugar-works of the field eringo, suddenly flies off, eager to stab the Cricket, the food of her grub?

It is a matter of memory, some will make haste to reply.

Ah no! Please do not speak of memory here; do not appeal to the belly’s powers of reminiscence! Man is fairly well endowed with mnemonic aptitudes. Yet which of us has retained the least [64]recollection of his mother’s milk? If we had never seen a babe at the breast, we could never suspect that we began life in the same fashion.

This food of earliest infancy is not remembered; it is certified only by example, as by that of the Lamb, which, with bended knees and frisking tail, sucks at the udder and butts it with its head. No, the mouthfuls of mother’s milk have left not a trace in the mind.

And you would have it that the insect, after a transformation that has changed it entirely, both inside and out, remembers its first diet, when we ourselves, who are not remoulded in the crucible of a metamorphosis, remain in the most absolute darkness where ours is concerned! My credulity will not go to that length.

How then does the mother, whose diet is different, distinguish what suits her offspring? I do not know, I never shall know. It is an inviolable secret. The mother herself does not know. What does the stomach know of its masterly chemistry? Nothing. What does the heart know of its wonderful hydraulics? Nothing. The pregnant mother, when establishing her brood, knows no more.

And this unconsciousness provides us with an admirable solution of the difficult problem of victuals. A good example is afforded by the Weevils whom we have just been considering. They will show us with what botanical tact the choice of the food-plant is made.[65]

To entrust the batch of eggs to this or that cluster of florets is not a matter of indifference. It is indispensable that the florets should fulfil certain conditions of flavour, stability, hairiness, and other qualities appreciated by the grub. Its selection, therefore, demands a nice botanical discrimination which will recognize off-hand the good and the bad, accept the discovery or reject it. Let us devote a few lines to these Weevils from the point of view of their botanical attainments.

Scorning variety, the Spotted Larinus is a specialist of immovable convictions. Her domain is the blue ball of the echinops, an exclusive domain, valueless to the others. She alone appreciates it, she alone exploits it; and nothing else suits her.

This particularity, an unchangeable family inheritance, must greatly facilitate her search. When, on the return of the warm weather, the insect leaves her hiding-place, which is doubtless not far from the spot where she was born, she easily finds, on the banks by the road-side, her favourite plant, which is already tipping its branches with pale-blue globes. The dear heritage is recognized without hesitation. She climbs into it, rejoices in her nuptial diversions and waits for the azure balls to mature to the requisite stage. The blue thistle is familiar to her though she sees it for the first time. It was the only one known in the past; it is the only one known in the present. There is no confusion possible.[66]

The second Larinus, the Bear, begins to vary her flora to some extent. I know that she has two establishments: the corymbed carlina in the plain and the acanthus-leaved carlina on the slopes of Mont Ventoux.7

To those who stop at the general aspect and do not have recourse to delicate floral analyses, the two plants have nothing in common. The countryman, clever though he be at distinguishing one plant from another, would never think of calling the two by the same generic name. As for the civilized townsman, unless he be a botanist, don’t speak of him: his testimony here would be worse than useless.

The corymbed carlina has a tall, slender stem; thin, sparse leaves; a bunch of average flowers, with a receptacle less than half the size of an acorn. The acanthus-leaved carlina spreads, level with the soil, a large, fierce rosette of broad leaves which in shape is not unlike the ornament of a Corinthian capital. There is no stem. In the centre of the leaf-cluster is a flower, one only, but a giant, big as a man’s fist.

The people of Mont Ventoux call this magnificent thistle the ‘mountain artichoke.’ They gather it and use the base of the flower in making omelettes not devoid of merit; this base is very fleshy, is saturated in milk with a nutty flavour and is delicious even when raw.[67]

Sometimes they use the plant as an hygrometer. Nailed to the lintel of the byre, the carlina closes its flower when the air is moist and opens it in a superb sun of golden scales when the air is dry. With beauty added, it is the inverse equivalent of the celebrated rose of Jericho, an unsightly bundle which expands in wet and shrivels in dry weather. If the rustic hygrometer were a foreigner, it would be famous; being an ordinary product of Mont Ventoux, it is slighted.

The Larinus, for her part, knows it very well, not as a meteorological apparatus, a very useless thing to her for foretelling the weather, but as provender for her family. Many a time, on my excursions in July and August, I have seen the Bear Weevil very busy on the mountain artichoke wide open in the sun. There is no doubt what she was doing there: she was attending to her eggs.

I regret that my then preoccupations, which were concerned with botany, did not permit me to observe the mother’s methods more closely. Does she lay several eggs in this rich morsel? There is enough to satisfy a numerous brood. Or does she lay only one, repeating here what she does on the corymbed carlina, a middling ration? There is nothing to tell us that the insect is not to some extent versed in domestic economy and does not proportion the number of the guests to the abundance of the provisions.

If this point is obscure, another and one of [68]greater interest is quite evident: the Bear Larinus is a clear-sighted botanist. She recognizes as carlina, the family food, two very dissimilar plants, which none of us, unless he were an expert, would have thought of grouping together; she accepts as botanical equivalents the gorgeous rosette, eighteen inches across, whose spokes lie on the ground, and the shabby-looking thistle that stands erect and spare.

The Spangled Larinus extends her domain still farther. Though she has not the fierce thistle with the white heads, she recognizes the good qualities of another vegetable horror, one with pink heads this time. This is the common horse-thistle (Cirsium lanceolatum, Scop.). The difference in the colour of the flowers causes her no hesitation.

Can she be apprised by the majestic stature, by the sturdy prickles? No, for we next see her established on a humble and much less savage plant, Carduus nigrescens, Vill., which rises hardly more than nine inches from the ground.

Can it be the size of the heads that regulates her choice? Not so, either, for the paltry heads of Carduus tenuiflorus, Cart., are accepted as readily as the sizable blooms of the above three thistles.

But the subtle expert is even cleverer than this. Regardless of mien, foliage, flavour or colour, she actively exploits Kentrophyllum lanatum, D. C., [69]a plant with wretched yellow flowers soiled by the dust of the roads. To recognize a Carduacea in this dry and unsightly plant you have to be a botanist or a Weevil.

A fourth Larinus (L. scolymi, Oliv.) surpasses the Spangled Larinus. We find her at work on the garden artichoke and the garden cardoon, both of them giants that lift their great blue heads to a height of six feet and more. We meet her afterwards on a niggardly centaury (Centaurea aspera, Lin.), with ragged heads, smaller than the tip of one’s little finger, trailing on the ground; we see her founding colonies on the various thistles beloved of the Spangled Larinus, even on Kentrophyllum lanatum. Her botanical knowledge of plants so dissimilar gives us food for reflection.

As a Weevil, she recognizes very clearly, without resorting to tests, what is artichoke-heart and what is not, what suits her offspring and what would harm it; and I, as a naturalist, versed by assiduous practice in the flora of my district, would not dare, without prudent inquiries, to bite into this or that fruit or berry were I suddenly transported to another country.

She is born with her knowledge; and I have to learn. Every summer, with superb audacity, she goes from her thistle to various others which, having no similarity of appearance, ought, one would think, to be rejected as suspicious hostelries. On the contrary, she accepts them, recognizes [70]them as her own; and her confidence is never betrayed.

Her guide is instinct, which instructs her unerringly, within a very restricted circle; mine is intelligence, which gropes, seeks, goes astray, finds its way again and ends by soaring with an incomparable flight. The Larinus knows the flora of the thistles without having learnt it; man knows the flora of the world after long study. The domain of instinct is a speck; that of intelligence is the universe.

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