THE PHYLLOXERA (Continued)

“The yellow plant-louse found on the roots of the grape-vine,” resumed Uncle Paul, “has no bent for traveling: wingless, sluggish, and big-bellied, it is ill adapted to locomotion. Where once its sucker has implanted itself, there the creature is glad to abide as long as the place is tenable. But when the rootlet dies and begins to decay, then a new refectory must be sought out, with a better-furnished table. Accordingly the louse has to move. A persistent explorer, it knows how, with patience and in course of time, to make its way through cracks in the soil from one root to another, and dares even to climb to the surface, where, proceeding in the open air, it emigrates from the exhausted vine-stock to the neighboring one rich in sap; and there it pushes down to the roots through some fissure in the ground.

“To this slow-goer a single one of our steps would be a journey of excessive length. Therefore, to propagate its kind far and wide, it must have other and quicker means than the extremely deliberate method of locomotion just described. This other method for planting colonies at a considerable distance has already been illustrated for us by the [289]green louse of the rosebush. Like that species, the phylloxera has a special division of winged travelers, and it is these that propagate the race throughout the grape-growing district.

“At the time of the greatest midsummer heat there make their appearance, amid the throng of yellow lice covering the roots, certain individuals with longer bodies, which soon change their skin and then bear on their sides two pairs of black stumps, the sheaths of four future wings. These are the nymphs destined for emigration. These nymphs leave their subterranean abode and climb up to the foot of the vine-stock, or sometimes even out upon the surface of the ground. There another change of skin takes place, whereupon we behold the winged insect, superior in form to its underground relatives.

“It measures a little more than a millimeter in length, not including the wings. These latter, transparent and iridescent, extend far beyond the length of the body, and the upper ones are wide, rounded, and slightly smoke-colored at the end, the lower ones narrow and shorter. They are supported by strong sinews that denote great power of flight. With its large, diaphanous wings, its broad head and big eyes, its belly ending in a blunt point, and its yellowish color, the traveling insect bears some resemblance to a very small cicada. Such, in brief, is the phylloxera commissioned to propagate the race at a distance.

“We have here no longer to do with the sluggish pot-bellied creature that needs all its strength to [290]move from one root to the next adjoining; we behold an agile denizen of the air, capable of covering with the swiftness of an arrow a distance of several leagues, especially when aided by a favorable wind. During the warm season of July and August these winged insects take flight and settle in swarms on the vineyards not yet ravaged. They alight on the leaves, where their suckers perform their function in sober moderation.

“To stuff themselves like gluttons, after the manner of their kindred that live on the roots, is not their way. Hence their own depredations are of no importance. Unfortunately, however, it is their mission to do us a most disastrous disservice by infesting, one after another, the adjacent vineyards, peopling the still unaffected districts with underground ravagers. All take part in this; all, without exception, set to work laying eggs.

“These eggs are few in number, it is true, each insect laying at most but half a score amid the cotton-like down of the buds and young leaves. But the aggregate is none the less enormous, since in this strange family we have thus far encountered none but mothers. We have just seen that all the wingless phylloxeras on the roots lay eggs, and now we find that all their winged kindred on the leaves do likewise.

“This excessive fecundity would in the end exhaust the insect and result in its extinction if there were no seasons of quietude for renewing the vitality of the race. Yellowish in color like the eggs of [291]the underground phylloxera, those of the winged insect are of two kinds: one of a larger size, the other only about half as large. The first produce females, the second males. Here, at last, we have the two sexes, whose coöperation will assure indefinite prosperity to the race. That is the normal order governing all animal life.

“But what queer little creatures! Yellow, wingless, stubby, they look like the lice on the roots, but even smaller. These phylloxeras of the third kind are dwarfs in a family of dwarfs. They have no stomachs for digesting, no suckers for puncturing the leaves and extracting their sap. Self-nourishment, however slight, is not at all their affair. The laying of eggs that shall renew the vigor of the race, the placing of them where they will be safe, and then a speedy death—that is the sole purpose of their brief span of life.

“For some days these dwarfs, male and female, wander over the vines and mate, one with another; then, in the fissures of the wrinkled bark, the mothers lay each an egg, a single egg, of enormous size in comparison with the smallness of the layer, greenish in color and sprinkled with fine black spots. This egg takes the name of ‘winter egg,’ being destined to pass the cold season fastened by a little hook to the vine’s bark. After this the layer of the egg shrivels up into a reddish point and dies.”

“But how do these eggs manage to get through the winter without freezing?” asked Louis. “Hens’ [292]eggs or birds’ eggs would be good for nothing after being left out-doors from autumn till spring.”

“That is true,” assented Uncle Paul; “nevertheless these minute germs of future insect life seldom fail to hatch when warm weather returns. From them come plant-lice like those on the roots of the vine. Each new-born louse crawls down the natal vine, hunts around on the ground until it finds a crack in the soil, and then makes its way through this fissure to settle at last on a rootlet, into which it plunges its sucker. At ease thenceforth beneath the surface of the ground and in the bosom of abundance, it does not long remain alone. Close to its fixed position it deposits its little heap of yellow eggs, whence there quickly issues a new generation. In like manner each member of the family surrounds itself with a family of its own; and so on by several successive repetitions of the process until, from having but a single occupant at first, a root speedily becomes covered with a legion of destroyers. To this population of recent origin we must not forget to add the older inhabitants that have passed the winter under ground and have only waited for the return of the warm season to resume their own laying of eggs on the roots of the vine.

“Let us recapitulate these singular ways of the phylloxera. The species comprises three forms of insects, each having its own peculiar structure, its manner of life, its separate function. The customary animal unity is here a trinity: three different insects are grouped in a single species.[293]

“The sedentary members are wingless and live on the roots. All lay eggs and are followed by several generations likewise capable of laying eggs. Under the pricking of their collective suckers, numberless in the aggregate, vineyards are ruined. There we have the formidable foe, the ravager whose sucker, hardly visible to the naked eye, has already cost us more than ten milliard francs.

“The migrating members are furnished with large wings. They live on the leaves and lay each a small number of eggs in the down of the buds. Like their sedentary kinsfolk, they all lay eggs. Their peculiar office is to disseminate the race from one vineyard to another.

“The members endowed with sex come under the operation of the general law: they are divided into male and female. Unprovided with wings, sucker, or stomach, they wander over the vine without taking any nourishment. Each mother lays a single egg, the winter egg, whence issues in the spring a sedentary phylloxera, which makes its way down to the roots, establishes itself there, and becomes the head and center of a new colony.

“How contend against this foe which, by reason of its numbers and its underground abode, defies our attempts to exterminate it? Three principal methods are employed. In the lowlands the vineyards are flooded and kept under a good depth of water throughout the winter. This submersion causes the death of the phylloxera at the roots of the plant. As a second method, through holes bored to the roots [294]the soil is injected with an asphyxiating fluid called sulphur of carbon, the fumes of which instantly kill all insects that they reach. The difficulty is to do a thorough job and leave no survivors. A third device is employed by those who import from America certain wild vines much hardier than our cultivated ones, but producing inferior fruit. These American plants resist the attacks of the phylloxera, and continue to flourish where our vines would succumb. On these wild stocks, as soon as they are well rooted, are grafted our native vines, and thus is obtained a grape-vine of two-fold quality, resisting by the hardy nature of its root the phylloxera’s assaults, and bearing, on its engrafted shoots, the incomparable fruit of our old vineyards.”