74 On the Mean? of preventing f 



at harvest, a sufficient quantity of wheat for. domestic uses, and, in- 

 deed, that they sometimes failed to reap the amount of the "seed they 

 had sown *." During the period that the Hessian fly was so cele- 

 brated for the mischief it occasioned, the Government of this country, 

 prevented the introduction of wheat from America. Such precau- 

 tions are not useless. The Egyptian bean has an insect in it of con- 

 siderable magnitude, which completely devours tbe kernel of the bean 

 before it becomes visible. This species of bean has been raised in 

 some parts of England, and the same insect is produced. Some 

 means should be adopted, to prevent the dissemination of so pernicious 

 a production, otherwise the public will sustain a very considerable in- 

 jury, which, by wise precautions, may ba prevented. Any risk of 

 this mischief spreading might have been prevented, had a public in- 

 stitution existed, to warn the farmer of his danger from its dissemina- 

 tion. 



Jn the years 1787 and 1788, the greater part of the southern pro- 

 vinces of America, were infested with another insect, called there the 

 " Flying Weevil" which, when full grown, is a minute moth, some- 

 what resembling that which breeds in, and destroys woollen cloths. 

 This insect is unfortunately well known in Europe as well as America. 

 In fact, it seems to be the same insect that is called " The Wheat- 

 Fly" in this country, and which has recently been so destructive in 

 several districts. 



3. Great Britain. The mischief done by the wheat-fly in various 

 parts of the kingdom, in the course of the year 1829, and the two pre- 

 ceding years, is frightful to contemplate. In one district in Scotland, 

 (the Carse of Gowrie, in Perthshire,) the destruction it occa- 

 sioned was estimated at little short of forty thousand pounds -j-. In 

 many cases, the crop was not worth the cutting down ; and in other 

 instances, a fourth, a third, or even a half of the produce was de- 

 stroyed. The myriads of this vermin, and the facility with which 

 they fly from one field to another, in search of the plants in which 

 their eggs can be safely and efficaciously deposited, seem to place 

 their depredations beyond the powers of man to controul ; and hence 

 it has been asserted, that the only means of avoiding the mischief is, 

 either to give up the culture of wheat until the race is destroyed, by 

 the want of the plants necessary for continuing the species, or by pa- 

 tiently waiting, until seasons destructive to them naturally occur. If 

 Providence however, has created so destructive an insect, as the ti- 

 pula tritici, or wheat-fly, it has been no less attentive, to prevent its 

 becoming too numerous, by making it the food of other insects. In- 

 deed, there are no less than three ichneumons J who seem to be in- 

 trusted with the important office of restraining, within due limits, the 

 numbers of this destructive species, otherwise it would become too 



* See Malcolm's Survey of Surrey, vol. ii. p. 258, on the authority of Dr 

 Mitchell of America. 



f Mr Gorrie, an eminent gardener in the Carse, calculates it at L.36,000. 



f Trans, of the Linnaean Society, vol. v. p. 102, where they are desciibed by 

 Mr Kirby. 



