1835.] 



FARMERS' REGISTER. 



815 



with another insect, called there the "JFlying JVee- 

 W(7," which, when full grown, is a minute moth, some- 

 what resembling that which breeds in, and destroys 

 woollen clothes. 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 re- 

 cently been so destructive in several districts. 



3. Gredt Britain . — The mischief done by the 

 wheat-fly in various parts of the kingdom, in the 

 course of the year 1829, and the two preceding 

 years, is frightful to contemplate. In one district 

 in Scotland, (the Carse of Gowrie, in Perthshire,) 

 the destruction it occasioned was estimated at little 

 short of forty thousand pounds.* 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 destroyed. 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 de- 

 posited, seem to place their depredations beyond 

 the powers of man to control; 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 

 patiently waiting, until seasons destructive to them 

 naturally occur. If Providence however, has cre- 

 ated so destructive an insect, as the tipula tritici, 

 or wheat-fly, it has been no less attentive, to pre- 

 vent its becoming too numerous, by making it the 

 food of other insects. Indeed, there are no less 

 than three ichneumons^ who seem to be intrusted 

 with the important office of restraining, within due 

 limits, the numbers of this destructive species, 

 otherwise it would become too numerous to be 

 subdued. The most extraordinary circumstance 

 is, that one species of these ichneumons lays an 

 egg near the egg of the fly. They are hatched at 

 the same time; and it is ascertained, that the mag- 

 got from the egg of the ichneumon, either lays its 

 egg in thejjody of the caterpillar, when it can get 

 at it, or devours the maggot, and thus preserves 

 the wheat from its attacks. J 



It is not here proposed, to enter into any phil- 

 osophical discussion regarding the origin of the 

 wheat-fly. It is sufficient to remark, that in the 

 spring, and in the beginning of the summer, a spe- 

 cies of fly is frequently found, in great numbers, 

 which attaches itself to the heads of wheat, when 

 the ear begins to appear, and where it deposites its 

 eggs, which in about ten days after they are placed 

 in the ears, become maggots or caterpillars. These 

 destroy the young pickle, by sucking up the milky 

 juice which swells the grain, and thus, depriving 

 it of part, and in some cases perhaps the whole of 

 its moisture, cause it to shrink up, and so to be- 

 come, what in the western parts of England is 

 called pungled.§ In about three weeks after, when 



* Mr. Gorrie, an eminent gardener in the Carse, cal- 

 culates it at £36,000. 



f Trans, of the Linnaean Society, vol. v. p. 102, 

 where they are described by Mr. Kerby. 



J See this interesting fact explained in the Quarterly 

 Journal of Agriculture, published by the Highland So- 

 ciety, No. 5, p. 301. 



§ See Transactions of the Linnaean Seciety, vol. iii. 

 p. 302, 



it has exhausted this substance, it drops upon the 

 ground, where it shelters itself at the depth of 

 about half an inch from the surface. There it re- 

 mains in a dormant state, until the mean tempera- 

 ture is about 50°, when, vivified by the warmth 

 of spring, it becomes a fly, about the time that the 

 wheat produces the ear. 



It is evident, that the same plan, that in our cli- 

 mate has been found so effectual for destroying 

 the wire-worm, would be equally destructive 

 to the wheat-fly, namely, that of leaving the soil 

 which has produced the wheat untouched till No- 

 vember, and then exposing it to the inclemency of 

 the weather, and in particular to the action of 

 frost. 



The great difficulty attending this plan is, to de- 

 vise an advantageous course of crops, consistent 

 with the idea of putting ofi the ploughing of the 

 wheat stubble till November or spring. In the 

 celebrated four years' rotation, 1. Turnips, 2. Bar- 

 ley, 3. Clover, 4. Wheat, the wheat stubble, as a 

 preparation lor the turnip crop, might first be 

 ploughed shallow, and then a deeper furrow taken, 

 by which the fly would be buried,* scarifying and 

 ploughing at the same time, and ploughing shal- 

 low in spring. 



I scarcely think it possible, that the fly can be 

 destroyed, if the wheat is succeeded by clover, 

 unless, perhaps, by severe rolling and treading. f 

 The minuteness of the caterpillar, which is no 

 bigger than the ordinary roman letter C, will pre- 

 serve it in a great measure from the effects of pres- 

 sure. 



It is a great advantage attending any plan for the 

 general destruction of this vermin, that the young 

 embryos are in general deposited in the fields 

 "where the wheat grew. "J Under a proper sys- 

 tem, therefore, the race might in a great measure 

 be extirpated in any particular district. It is abso- 

 lutely necessary however, that there should be a 

 general combination for that purpose. Nothing 

 done in the field where the new wheat is sown, can 

 be of any use, for the fly is produced in fields, not 

 under wheat at the time, and flies about, until it 

 finds a plant suitable for its purpose. 



In seasons, when the frost may not be supposed 

 sufficiently violent, the desirable object may be ob- 

 tained, by frequently stirring the ground, and by 

 rolling and treading it, or burning stubble upon the 

 surface, or by the use of hot-lime. Fumigations 

 of tobacco or sulphur, made when the wind is la- 

 vorablc, might also render the ear disagreeable to 

 this insect. § 



If other means are ineffectual, surrounding the 

 field of wheat with a belt of hemp, the smell of 



* This is a plan recommended by Mr. Gorrie in the 

 Carse of Gowrie. 



f An instrument, at the same time, might be invent- 

 ed, similar in principal to the machine used at bleach- 

 fields for beating linen, which would probably destroy 

 the maggots of the wheat-fly in the young clover by 

 compression. 



J Mr. Sheriff has ascertained, that embryos are like- 

 wise deposited in the triticum repens, or couch grass, 

 which delights to grow in hedges, and other neglected 

 situations; but these could easily be extirpated. 



§ Transactions of the Linnaean Society, vol. v. p. 

 10.3. 



