black.. Her fingers are contracted. (of which M. Noël had fent no acThe reft of the family feem to be, count) was produced by bad hourecovering perfect health. Wattisham, April 30, 1762. There is, in hiftoire de l'acalemie royale des Sciences, for the year 1710, à paper, the title of which is, Sur le bled cornu appellé rgot. Here it is faid, that M. Noël, furgeon of the hôtel-dieu at Orleans, had fent an account to a member of the academy, that, within about a year's time, he had received into the hofpital more than fifty patients afflicted d'une gangrene feche, noire, et livide, which began at the toes, and advanced more or lefs, being fometimes continued even to the thighs; and that he had only feen one patient, who had been firft feized with it in the hand. He adds, that he obferved, that this difeafe affected the men only; and that, in general, the females, except fome very young girls, were quite free from it. rifhment, particularly by bread; in which there was a great quantity of ergot §. This fubftance is defcribed by M. Fagon, firft phyfician to the king, and is faid by him to be a kind of moniter in vegetation, which a particular fort of rye, fown in March, is more apt to produce, than what is fown in the autumn, and which-often abounds in moist cold countries, and in wet feafons. How far it is true, that this fubftance was really the cause of the French epidemical gangrene defcribed, I cannot determine. On comparison, we find, that the prefent difeafe at Wattifham, and that recorded by the French academy, do agree extreme ly in their effects. However, it is now certain, that rye made no part of the nourishment of the poor family at Wattisham. Although we undoubtedly excel the ancients in the knowledge of poifons, yet a great deal of that fubject ftill remains unknown to us. It will, therefore, be very difficult for us to difcover, to what caufe, or to what combination of caufes, fo uncommon a malady is to be attributed. Account of the corn butterfly, which in its vermicular state lately ravaged whole provinces in France. A Very fmall infect, which till within a few years, has been unknown to the naturalists of every Secale corniculatum nigrum, mentioned as a poifon by Hoffman. This degenerated rye is called erget, from its refemblance to a cock's fpur." VOL. VI. country Country, has attracted the attention of the French government, by the ravages which it has committed in the province of Angoumois, where it is called the corn-butterfly. It was firft perceived about thirty years ago, and it has fince increafed to a degree fo alarming, that it has, in its vermicular state, deftroyed the most plentiful harvest in a few months. It begins to devour the grain while it is yet grow ing in the ear, it continues its ravages in the barn, and deftroys what is left in the granary, so that the inhabitants of the province are reduced to the neceffity of eating bread made of maize or oats; and the rich have retired to the neighbouring provinces. These facts having been reprefented to the miniftry by M. Pagot de Marcheval, the intendant of Limoge, by a memorial dated some time in 1760; the comptroller-general wrote to the royal academy of fciences, recommending it to them to fend proper perfons to examine this infect, and find fome remedy for the mifchief it produces. In confequence of this letter, Meff. Duhamel and Tillet were deputed to this fervice, and upon entering the province, they found no less than 200 parifhes entirely defolated by this infect. They were affifted in their enquiries and experiments by the neighbouring clergy and gentry, and in a particular manner by a lady, madame de Chaffeneuil, whofe abilities in making and pursuing experiments of this kind, are equal to thofe of the best naturalifts in the kingdom. The corn-butterfly of Angoumois is of the clafs of the phalena, it has antennæ that refemble a knotted thread, its wings, when not flying, meet over its back, floping like a pent-house, and are rather long for the breadth; they are of a colour fomewhat refembling that of milk coffee, yet they fhine in the fun, and are bordered with a deep fringe, efpecially on the inner fide; its head is hairy; the hair parts under the head into two tufts; it unites above, and paffes between the antennæ; it runs up from thence higher than the eyes, where it rises into a tuft like a toffel behind: at first view it would be taken for what is called the falfe moth, but it is an infect of a different species. This butterfly feems to be employed wholly in multiplying its kind; it couples in the night, or in fome dark place, and the conjunction lasts many hours; fometimes the fexes unite a fecond time after feparation: the eggs are depofited almost immediately after they are fecundified, in small parcels, each confifting of a certain number from 6 to 30, and each female lays in all from 60 to 90: the eggs are covered with a viscous juice, which caufes them to adhere to whatever they happen to be depofited upon, and are fo fmall, that they will drop through a hole made in a piece of paper with the point of the finest needle. When examined with a microscope, they appear to be firiped long ways, from top to bottom, and with a rough furface, refembling fhagreen. After the egg has been laid 4, 6, or 8 days, according to the temperament of the feafon, it produces a caterpillar about the thick nefs of an hair, and about the fortieth or fiftieth part of an inch long; this worm immediately hegins to introduce itfelf into the total heart P H heart of the grain; it infinuates itself first into the membrane, which feparates the two lobes, where it fpins fome threads of its filk, it then wounds the hufk with its teeth, but in fuch a manner, that when it has penetrated into the farinaceous part of the grain, the husk collapfes, and clofes the aper ture, fo as that it can scarce be perceived, even by an inquifitive eye. Many of them; however, perifh before they can get into the heart of the grain, either by fatigue or hunger, or by a conteft among themselves, which very frequently occurs to decide the property of a grain which happens to be attacked by feveral at the fame time. One of these caterpillars is always contented with one grain of corn, and never leaves that which it has penetrated to attempt another; but two of them are never found in the fame grain; one is fufficient to confume it entirely, and without any injury to the huk, it eats the contents of it fo clean, that nothing can be extract ed from what remains, even by foaking it in water. It seems probable, in the highest degree, that this worm having devoured all the farinaceous fubftance of the grain, eats its own excrements again and again. When it arrives at its full growth, which is about a quarter of an inch long, and about half the thickness of the grain it has confumed, it begins to fpin its cod; its body is without hair, and entirely white, it has two protuberances, like horns, upon its head, which are placed in a direction towards the tail, near which there are two others which have alfo the fame direction, and it has fix legs. This creature, as if it forefaw that in its butterfly ftate it would have no organ left to penetrate the hufk that inclofes it, has the precaution to fashion with its teeth, in that part of it which is overagainst the head of the chryfalis, a kind of trap door, large enough for the butterfly to iffue out at, which continues fhut till it has quitted the fhuck of the chryfalis : when this prudent meafure has been taken, the caterpillar fpins a cod of filk, which exactly fills one of the lobes of the grain, the other being filled with its excrements; the butterfly being difengaged from the chryfalis, forces his head thro the cod, lifts up the trap door which had been made in the hufk, and iffues out, as it were alive, from a tomb, in order to propagate its fpecies. Such is the circle of the life and transformations of this infect; but it is not easy to fix the precise time in which thefe transformations are effected, as they are retarded by cold, and accelerated by heat, confequently the number of generations which fucceed each other within a year cannot be ascertained: In the most favourable season a generation goes through all its func tions in about a month; but that which paffes the winter in the grain lafts feveral months, the duration of other generations may be fixed at a medium between thefe two extremes. Towards the end of May, or the beginning of June, eggs, or the caterpillars in a very diminutive state, are found upon the cars of the grain, as it is growing in the field; in July there are butterflies which depofit a new pofterity upon the fame ears, which gives birth to a fecond in the barn, G 2 ΟΙ The academifts to whom this matter was referred, fearched the fields by night in the fpring, with lanthorns in their hands, for the infects which were the objects of their enquiry, and found them in great numbers coupled upon the ears of the grain which was yet green; they communicated their difcovery to the inhabitants of the province, who then first underftood the origin of the caterpillars," which they found in June upon the ear, and of the butterflies which they faw iffue from it in July. or in the granary, towards the end way out of the granaries, and at of Auguft if the cold of the ap-fun-fet the fwarms are seen spreadproaching winter is kept back, a ing themfelves over the country, new brood is produced in Septem- from the windows, and from under ber, and another still in November, the eves of the granaries; the if that month happens to be mild; flights of the other feafons pafs the according to this computation there day in reft, and at night become are five generations of thefe ver- very active, flying here and there min in a year, but it is not necef- over the heaps of grain from which fary they fhould multiply fo faft to, they iffued, but none of thefe commit the most dreadful ravages. fwarms are ever seen without doors. It is, indeed, fomewhat difficult to diftinguifh exactly all their generations, becaufe butterflies are continually seen iffuing from heaps of grain, and each butterfly lives about a month; but at certain times a prodigious number iffue all at once, which is called a flight, and is always preceded by a coafiderable degree of heat, generated in the heaps of grain, which will caufe the thermometer to rife to 25. 30. and even fometimes to 50 degrees, when the external air will not raise it higher than 13 or 14. This heat may proceed either from the great number of caterpillars ready for their transformation, or from a general fermentation excited by an abundant transpiration, or even an evacuation of a certain liquor which generally precedes the transformation of the caterpillar into its chryfalis. This heat very confiderably favours the progrefs of the caterpillar through the feveral ftages of its existence; but when a flight is not at hand, the heat of the grain is very little greater than that of the external air. There are generally three flights in a year; one the latter end of May or the beginning of June, a fecond in Auguft, and a third in fome of the fubfequent months. The butterflies produced in the fpring flight, always make their This discovery explained alfo another phænomenon which might greatly have embarraffed them, and fhewed the reason why thofe crops fuffered moft from this infect, which were produced upon fields contiguous to towns and villages; it having been observed that every 16th, 20th, 30th, or 4eth grain of a crop was attacked, according to the granary's dillance from any habitation in which there was a corn chamber with grain in it in the fpring. The deputies of the academy broke up a piece of ground in 1760, in the foreit of Braconne, having no granary within a great diftance, and fowed it with grain which had been brought from a province which the infect had not yet infefted; but notwithstanding thefe thefe precautions, in the harveft of 1761 they found every 80th grain affected, though this crop was lefs damaged than any other in the province. It appears from this fact, that the corn-butterfly is capable of a long flight. The following calculation will hew the astonishing multiplication of thefe infects, and confequently the ravages which they make where they have already established themfelves, and with which all the neighbouring provinces are threatened. Every female produces from 60 to go eggs, of which 75 is the medium; but let us fuppofe the number to be no more than 70. Let us fuppofe alfo, that of thefe 70 eggs, one half only produce females, which makes the number 35. This multiplied by 70, the number of eggs laid by each, gives for the fecond brood from a fingle infect, 2450 the half of this number fuppofed to be females is 1225, which multiplied by 70, gives 85,750 for the third brood. Half of this number 42,875, multiplied by 70, gives for the fourth brood 3,001,250; half of this 1,500,625, multiplied by 70, gives 105,043,750 for the fifth brood: fo that, fuppofing five broods in a year, each female butterfly of this fpecies that exifts in May, produces, before the May following, no less than one hundred and five millions, forty-three thoufand, feven hundred and fifty individuals of the fame kind. It appeared alfo in the courfe of the experiments made upon thefe infects, that the caterpillars which were furprised by the winter before they had paffed their chryfalis fate, would furvive in the ground till the next fummer if they were not more than three inches below the furface, and the earth was not clofe, compact, and a little hard, in which cafes they would infalli bly perish. It appeared alfo that they would live and multiply in oats, as well as in wheat, barley, and rye, in which they were moft commonly found, and that the eggs were de pofited between the two grains that grow on one pedicle, which is faftened to the ftem that forms part of the ear, and that they would alfo be produced and thrive in Spanish wheat or maize, if maize was in a state to receive the eggs when the butterflies lay, which happily is not the cafe. The reader will now think it happy that a method has at last been difcovered, by which these destroyers of the ftaff of life may be extirpated, and the grain preferved from harvest to feed-time. [For this method fee our article of Projects for this year.] |