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ans have been very accurate in defcribing them, few have given any account of the means of preventing their increase, or of deftroying them. This neglect has induced me to collect a few obfervations on record upon this fubject, and fome which have occurred to myfulf. I requeit, that you will grant them a place in your very ufeful publication; for I flatter myself that, by others following this example, a foundation may be laid which in a few years may afford much ufeful information.

Every animal, by a law of Nature, nourishes, and often harbours, its peculiar infect. If we confider the damages we fuft in fro a their infatiable rapacity, it is happy that they have many enemies which alfo prey on them. Thus a fparrow and its mate deftroy many infects when they have young. It is probable, in purfuit of fuch reptiles,that we are vifited by fome of our beautiful fongfters.

many circumftances which are to us inconceivable; but fhall we thence conclude that they cannot be as their appearance indicates?

Let us fuppofe a cold North-eaft wind, for inftance, in fpring, to come on fuddenly, when the juices of plants circulate freely in their capillary veffels. The cold is known to stop the early circulation of the juices of plants. On the return of warnath, the circulation is reftored, and the ftagnated juices are extravafated. The organic particles, in thefe juices, are collected into the ftamina of the infect peculiar to each plant and thus the infinite number of caterpillars in fpring are produced. This effect may proceed from any other caufe which interrupts the circulation, or flops the perfpirable matter on the barks. In animals, in the fame manner, the component particles of the infe&ts peculiar to the animal may reft on, or in, the skin, by the neglect of not keeping them clean.

The question is, Whence thefe numerous fwarms of infects proceed? There feems to be a general law for producing the infe&s peculiar to each animal and plant, and even to infects themselves. Is it not probable that, for good purposes, the infinitely wife Creator did at the creation fo form all organized bodies, as at certain times, and in certain circumftances, to contain, or discharge from their bodies, particles which may coalefce into other, bodies poffefiing a living principle? When thefe are produced, they are enabled afterwards to produce their kind, as Buffon obferves of eels in pafte, which do not appear to be produced by other cels; yet, though they are not propagated themselves, they fail not to engender other eels; for, by opening them with the point of a lancet, we difcover fmall eels iffuing in great numbers out of their bodies. See Mr Adam'sexcellcat Eflays on Agriculture, v. II. p. 170.-When we revolve in our minds the general hiftory of animation, we fhall find

It is generally obferved, that infects feldom appear on either animals or vegetables while they are in perfect health, and have due care bellowed on them. When they appear, the caufe fhould be enquired into, in order that fuch calamities may be as much as posible prevented in future. Thus the loufe is peculiar to man, when cleanliness and care are wanting; or in fecond childhood, when attended with poverty. A loufe is a king's companion, faid a moft worthy king, efpecially in a camp. By the fleek fkins of horfes on whom due care is taken, we fee the advantage of keeping them clean. Plants, in wellcultivated fields, are feldom liable to become the prey of infects. pears from fuch instances, that, both in animals and vegetables, care in their infant ftate is of effential fervice.

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Inftead of pointing out the particular inconveniences which infects bring on animals or vegetables, I fhall now.

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mention fuch fubftances as have been generally obferved to be efficacious in driving away or in deftroying them. Mercury, and its various preparations, may be reckoned one of the moft generally useful. Sulphur is also ufe ful. Oils of all kinds have been often and defervedly recommended. Tobacco is not lefs remarkable for its utility. As early as the time of the Romans, thell-fith were obferved to be at least very difagreeable to infees. Of the application of thefe in order.

wash will effectually deftroy that dif agreeable infect the bug, and all other infects of a tender cuticle. This wath will not in the leaft hurt the colour of bed-furniture or hangings. Care must be taken that the with be applied into every crevice or folding of the furniture with a painter's bruin. It will fometimes be neceflary to repeat the wafh, as fome of the "ova" of bugs may remain concealed, notwithstanding the utmost care.

Some of the Weit India islands were much infefted with large ants, which greatly hurted the fugar canes. I was informed by a gentleman froni thence, that they diffolved corrofive fublimate mercury in rum, in the proportion of two drams to a pint of fpirits. They poured this folution on dry powder fugar; and when the fugar was dried, they laid it in the paths of the ants. They ate it, and were deftroyed. Might not this practice be imitated, by laying fugar thus prepared on paper or pieces of thin boards near the root of fruit-trees infeited by infects, efpecially when the fruit

might be taken in during the night, or when it rained. The fugar should be coloured with indigo, or other fubftance; thereby to mark it as a fubftance to be avoided by curious idlers.

Mercury is known to kill or drive away lice from the human body; and it may probably be of equal efficacy in ridding cther animals of their infects. For instance, fheep having a finall quantity of mercurial ointment rubbed on their fins, on the fides, between the forelegs and the body, it may kill or drive away the infect peculiar to them. Sulphur is recom mended to be added to the mercurial ointment. Thus, not only the infest peculiar to them, but alfo the fcab, may be cured. See the Tranfactions of the Society for the Encouragement is ripening? The papers or boards of Arts, London, vol. VII. VIII. p. 9o. In the Tranfactions of the fame Society, vol. V. VI. p. 59. Mr Ailway directed, that in the winter, the walls, the frames, &c. of his green and hot-houfes fhould be well washed with the following mixture: We are informed that a perfon in Take of corrofive fublimate mercury. Philadelphia employed brimstone in four ounces, and diffolve it in two the following manner :- Having cleargallons of water. Thefe houfes had ed all round the roots of trees infel been greatly infefled with red spiders ted with caterpilla.s or other infects, and ants. After having been washed he ftrewed fome flower of brimstone with the above mixture, neither were round the roots, and covered it with a to be feen next fummer. This wath thin fprinkling of fine mould, that it may be used on old garden walls, and might not be blown away by the wind, to the roots of fruit-trees infetted with yet fo that the fan might operate infects, if made weaker. It may through, and caufe the brimstone to deftroy the tender leaves of plants, fumigate. Thus he deftroyed the though not the roots. One pint and caterpillars. One pound he found a half, poured four months ago on a fufficient for two hundred trees. ftandard currant-tree, as near the that hot climate the fun may perhaps ftem as I could, had no bad effect have that effect; Lut it fcarcely will either on the leaves or the tree. This in this. He alfo employed fulphur

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in the following manner, to drive in fects from tall trees. He split the end of a pole, and put in the flit fome matches, fet them on fire, and held them under the parts of the trees chief ly affected. A pole thus armed, he found, would anfwer for three or four trees. Brimstone thus mixed with damp straw, and fet on fire, for inftance, in a hop-ground infested with the fly, might be of use to drive away the fly.

The itch is fuppofed to proceed from a very fmall infect which neft les under the fkin, and proceeds no farther into the habit; and is therefore attended with no dangerous confequences. Brimftone made into an ointment with hogs-lard is a fure remedy. Whether the cure proceeds from the brimstone or the oily lard, I fhall not determine.

Sheep are liable to an irruption on the fkin, known by the name of the fcab. The brimftone, when added to the mercurial ointment recommended for that diforder in the Tranf actions of the Society for the Encouragement of Arts, vol. VII. p. 90. might perhaps render the application more efficacious and lefs dangerous.

The natives of hot countries are taught by experience, that an unctuOus covering on their bodies prevents the bites of mufkitoes and all gnats. The White inhabitants in fuch countries are not fufficiently careful in preventing the leaft ftagnant water near their dwellings, in which the Muf kitoes are bred; even in the wafte water thrown out they are produced, Dr Franklin, that accurate obferver, informed me, that, by a careful attention to this circumitance, he guarded his family in Philadelphia from fuch infects and that one day feeing a number of mufkitoes in his library, he found on enquiry, that one of his fervants had taken the cover off a tub placed near his window for receiving rain water. On fuch an eccafion the remedy is eafy, viz. Tt VOL. XII. No. 71,

fhutting the room up for the day, fo that the mufkitoes cannot come at any water, in which time they die. Tho this caution may feem trifling to us who live in a mild climate, it is far otherwife in hot countries.

Oils being known to be moft efficacious in. deftroying infects, may not the use of it be extended to the deftruction of worms in the bowels of horfes, where they may occafion the violent pain they feem fometimes to fuffer? If the horfe was for fome time kept fafting, and a large quantity of oil, fuppofe a pint, was given, if worms are the caufe, the oil may in that cafe kill them. If I may venture into another line, may I not afk, whether the ufe of it is not too little attended to as an anthelmintic medicine in the cafe of worms in the human body? Being injected by glifter,it is known to bring away the afcarides, a fmall worm which feldom afcends higher than the rectum, or the last gut.

Flowers, leaves, and fruit, on plants, are known to be devoured by caterpillars. Thefe are deftroyed by oils, which clofe the lateral pores by which they breathe. For this purpofe it is advited, that, on the approach of fring, a cloth dipped

in train-oil be laid on fuch parts of the tree in which there is the leaft appearance of them.

We are informed, in the Memoirs of the Society of Agriculture at Paris, that oil of turpentine, when applied to animals which were covered with infects, deftroyed the infects without hurting the animal. The author tried it on fevera! trees, mixed with fine earth fo as to incorporate them well, then adding water, ftill ftirring them carefully till the whole was brought to fome degree of fluidity. In this mixture he dipped branches of fruit-trees on which there were infects, and hereby deftroyed not only the eggs, but allo the infects, without hurting the leaves. This compofition may be got off by

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washing, or the firft heavy fhower. From thefe experiments the author thinks, that oil of turpentine may with equal efficacy be employed for killing various kinds of lice on domeftic animals.

We are informed, in the Tranfactions of the Society for the Encouragement of Arts, vol. V. p. 45, that Mr Winter, among other experiments on turnep-feed, fteeped the feed twenty-four hours in a fufficient quantity of train.oil. He then drained the oil from the feed, which he mixed with a quantity of fine-fifted earth, and immediately fowed it in drills. When the plants began to appear on the furface, the ground was fown with foot. He found that feed fteeped in lintfeed-oil answered equally well. The turneps the leaft injured by the fly were those that grew from feed fteeped as above, which grew fo lux-' uriantly as to produce rough leaves feveral days prior to the moft flourifhing of any of his other experiments, and were the better enabled to withftand the fly's attack. The leaves of thefe turneps were of a dai ker green, and appeared to be twice as thick in bulk and luxuriancy, than the other turneps, and were a confiderable deal larger. The feed was drilled an inch and a half deep, and at a foot distance in the rows. Train oil is apt to kill the leaves of plants which have been injured by infects, but lintfeed-oil has not that effect, though equally deftructive to the infects. The rain-oil feems to act both as an oil, and by its difagreeable fmell it prevents infects approaching it. In this refpect it may be fuccefsfully used to prevent field-mice or other vermin preying on acorns,cheftnuts, or other feeds steeped in it before they are fown.

When thus giving directions for preventing the fly on turneps, late experiment fhould be mentioned, by the difalofing of which, a man gained a confiderable reward. His fecret was, running a roller over the ground early in the morning, while

the dew remained on the ground, on the first appearance of the fly. The dew entangled the flies fo much, that they could not make their escape, and were therefore crushed to death. As the roller may leave the furface of the earth too hard, fome very properly advife to fix fome boughs of elder in a gate or hurdle, to be drawn over the field; and if the boughs have been before fumigated with the fmoke of tobacco, or tincture of affafoetida, the fuccefs will be the furer. The most certain method of preventing the hurt done by the fly is to raise the plants in a nursery, and at a proper age to tranfplant them, being carried to the ground in a wheelbarrow filled with manure foftened with water fo as to admit the plants. This method will fecure their more speedy growth. In the nursery the attack of the fly may be prevented by spriok-ling foot or quicklime on the ground. The utility of tranfplanting turneps evident by the practice of tranfplanting the turnep-rooted cabbage. They who are difcouraged from this practice by the expence attending it, do not reflect that the hoeing is prevented, and the plants grow the better, being fet in frefh earth.

Before I proceed to direct the ufe of the laft means mentioned, viz. tobacco, for deftroying infects in turneps, let me here mention an experiment made by a worthy and ingenious man, Mr Green, of her Majefty's Flower-Garden at Kew. He contrived a pair of bellows, fimilar to that employed in recovering people feemingly drowned. It has a cavity in the nozzle, in which fome tobacco is put, a live coal over it. The bellows being then worked, the tobac co is fet on the fire, and the smoke is directed to any particular spot. A lady was fond of having the moskrofe in her dreffing-room, but was prevented having it on account of the green infects which conftantly adhere to that plant. To remedy this inconvenience, Mr Green had a box

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made large enough to contain a pot in which a plant of the mofk-rofe grew. In one end of the box was a hole, to admit the nozzle of the bellows; the bellows was worked, and the smoke was received into the box. When the tobacco was confumed, the nozzle was withdrawn, and a cork being put into the hole, the box thus remained till morning, when the infects were all laid dead onthe earth. Being fwept off, the plant was in a state fit for a dreffing-room. Many plants thus infefted with infects may be too large, or otherwise fo placed as not to be put into a box. In this cafe it occurred to me, that being fprinkled = with an infufion of tobacco in water might in fome degree anfwer the fame purpofe. On trial I found it anfwer, and I thus freed other plants of their infects. I also used it on trees of ea. fy accefs with advantage. Train-oil is fo inimical to tender plants or leaves, that it deftroys them if infects have in the leaft hurt them; whereas the infufion, inftead of killing the leaves, promoted a fresh vegetation.

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Fruit trees often become the of infects. Those against a wall, or in efpaliers, being easily come at, much of the mifchief may be prevented by cutting off the leaves fo foon as they are obferved to be curled; for then fresh eggs are laid on them, probably by butterflies. If fprinkled with the infufion of tobacco, It will prevent their coming to life. After the fruit is formed, the infufion must not be used, leaft the talte and smell may remain. The fciffars are then the proper remedies, which ladies may employ as an amufement, and may thereby prefent fruit to their friends of their own preferving. A lye of the ashes of plants:fprinkled on the leaves may have a good effect, as alfo on other pot-herbs, which are often the prey of caterpillars. As many infects, befides thofe bred on the leaves or in the walls, may deftroy the fruit, the fugar with the cor

rofive fublimate, as already described, may be laid in the way of other infects, to all which it will prove a fpeedy death. Diligent inspection into their retreats is the most certain means of preventing the lofs fuftained by fnails. Ants are prevented fing up the trees, by laying round the roots powdered chalk, or any other fubftance which by intangling their feet prevents their croffing it. Care fhould be taken to destroy their nefts every where near the garden.

Hops are now become an article of fo great confequence, that they deferve our particular attention. Early in the growth, when the vines begin to afcend the poles, a black fly preys on the leaves, frequently in fuch numbers, as, by deftroying the leaves, to interrupt the vegetation, much of the food of plants being abforbed by the leaves. I know by experiments that the infufion of tobacco deftroys them, or at leaft drives them away fo effectually, that I have feen a plant, almoft totally ftripped of its leaves, fhoot out fresh leaves after the use of it. If care be not taken, they will again fall on the fresh leaves. As the flies lodge on the lower fide of the leaves, they are protected from ftorms of rain, and therefore the infufion must be driven upwards by a forcing pump. As it is faid that the expence of tobacco is too great, perhaps lime-water, or even water by itfelf, driven strongly agaiuft the leaves, might drive them away. The labour attending fuch experiments in a large plantation difcourages others, without reflecting that, if fuch means are ufed early, the flies may more easily be got rid of.-Free ventilation is undoubtedly beneficial to all plants; and hence perhaps the particular advantages of drilling corn in rows a little diftant. If alieys fomewhat larger than common were made in the plantations of hops, there might be fufficient fpaces left where the alleys crofs one another to admit of fetting Tiz

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