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come too near thefe delicate bodies, which can hardly be touched without hurting them. All places are not equally fit for them; they fhould neither be too dry, nor too moift, nor fubject to be infested by such infects as they have an antipathy at, or which are reftlefs and turbulent. Of all expofures the least favourable are thofe of the north and fouth. The winds from thefe two quarters are exceedingly pernicious to them, the one by its coldness, the other by its humidity; for which reafon, it is neceffary, that the place be fo difpofed, as that its temperature may be regulated, by fhutting the windows on one fide, and keeping them open on the other, according as the wind fhall blow from the north or fouth. When the weather is moist, it is proper to keep the place quite clofe; but when it lightens, that is not fufficient; the filk worms must be covered up, otherwife they contract a difeafe, which fome curious perfons have thought proper to term jaundice. They do indeed acquire a yellow colour, lofe their appetite, and die infenfibly. Thofe that die, fhould be feparated from the living, for fear of communicating infection to them..

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BOOK II.

PART III.

CHAP. I.

How INSECTS HURT THE PRODUCE OF THE EARTH,

Not only do infects pillage and ravage the fields, but they attack man in his domeftic economy, and do him infinite mifchief. Nothing can be protected against their ordure; we fee, with regret, our moft precious furniture tarnifhed and infected by flies. Thefe reftlefs infects enter our libraries, neftle in our cabinets, pafs from one apartment to another, and leave every where behind them, the moft confpicuous 'marks of their having been prefent. There is not a man, from the king to the pooreft of his fubjects, who can defend himself against their attacks.

Husbandmen perhaps are the moft to be pitied. How often do they not find themfelves difappointed of a plentiful crop by the depredations of locufts! Thefe voracious animals often leave diftant countries, traverfe oceans, pour in myriads upon fown fields, and deprive them in a few hours of every appearance of

of verdure. Are not caterpillars often as noxious to us? I know not a more cruel fcourge for gardens than they are. They eat into flowers, they gnaw the roots, and fo deftroy the plants they touch, that we are obliged to throw them away. Some do not wait till a plant is able to furnish them food for weeks, they devour it the moment it appears. Others on the contrary wait till the feed is produced; they then devour it fo greedily, that nothing is left but the empty fkin to the owner. Weevils are not behind hand with thefe; they pierce the ripe grain, eat the pulp, and thus rob our granaries of that food which is of the greatest importance to the human

race.

But it is not on herbaceous plants alone, that infects bring ruin; their attacks are not lefs difaftrous to fruit trees. If they depofit their eggs in autumn, the young caterpillars are hatched in the Spring when the trees are only beginning to fhoot forth, and they commit fuch ravages on the buds and foliage, that wherever they are found in numbers, the fruits of the year entirely fail. The fmall Curculios, fome beetles. and feveral forts of caterpillars confpire in producing this devaftation, and fometimes reduce the trees to the fame state they were in during winter. This is not all, for there are some forts of golden coloured beetles which produce two forts of larvæ, red and white. Thefe larvæ penetrate the bark, and fuck the juice till the tree becomes completely dried up. There are alfo fome fmall beetles which, not content with eating the bark, attack the wood, and contrive to defolate whole forefts. This accident has but too often happened with woods planted with pines. The wood of Schwartzenburg experienced this to fuch a degree in the year 1736, as coft its proprietor many thousand crowns. I fhall content myfelf with this one example; thofe which I could adduce of many other forts

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which deftroy wood are too common not to be known by every one,

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We have spoken of the ravages which infects make both in the country and in towns; let us now take a view of the mifchiefs they occafion to man himself perfonally. Some difturb his fleep, others oblige him to pafs whole nights without fleeping at all. Indeed, what does he not fometimes fuffer from the reftlefs flea, and the loathfome bug? How can he take reft when unhappy enough to be expofed to the fanguinary infults of fuch tormentors? But were he free from thefe, the gnats do not cease to perfecute him. Their inceflant buzzing difquiets him, and whether asleep or awake, while in darknefs he is equally a prey to thofe ftings which he dreads but which he cannot prevent. In the Eaft Indies the inhabitants are exceedingly tormented by those infects which the Portuguese call Mofquitoes. These dangerous animals dart upon those whom they furprize afleep, and in fuch prodigious numbers that it is no eafy matter to refift them. When one is ftung in the face, or in any other part of the body, there enfues a confiderable tumour, accompanied with itching and intolerable pain.

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There is another kind of infects which are hurtful to man by mere touch. Such is the Scolopendra marina, which caufes a pricking in the skin, and a heat fimilar to that which one feels after having touched the common nettle. Among thofe which render themselves formidable by their prickles, fome have · the hair fo acute that they wound almoft imperceptibly, occafioning an inflammation which quickly brings on fever; others, as the hornet and bee, ftrike with their fting, and though the wounded part does not bleed, it does not fuffer the lefs, and a fenfible fwelling fucceeds. Befides thefe different infects there are others which like the gad fly have ftings fo fharp and ftrong that they can pierce the fkin through gloves and ftockings; others are remarkable by their bite like fpiders; and fome attach themfelves to our bodies and fuck the blood. The Eaft Indies fwarm with leeches, to which the Dutch have given the name of Snygers. They lurk in general among the grafs, when the dew has moiftened the ground, and as the country, which is interfected by rivers, torrents and fwamps, obliges travellers to walk for the most part with naked feet, it happens that thefe animals cling to the legs and gorge themfelves fo with blood, that they fall off fpontaneously. There are fome fo greedy that they thrust their head into the fkin as far as the neck, and the only method of making them quit their hold, is by furrounding them with moistened gun powder, when they will come away of themselves in about a quarter of an hour or thereabouts. If a perfon ignorant of this expedient fhould think of employing force to detach these animals fuddenly, he would pay dearly for his impru dence. Not only would he experience violent pain, but a part would remain in the fkin, engender an abfcefs, and corrode the flesh to a great depth. I appeal for the truth of this to the fad experience of many perfons who for feveral years have been subject to fuppurations

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