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238 QUARTERLY JOURNAL. 



above statement, and says, "At that time I did not know that a 

 yellow fly had deposited the eggs within the glume, which became 

 maggots. Observing numbers of black flies on the ears of wheat, I 

 believed they had been the produce of the caterpillar. I have this 

 season, however, observed the yellow fly (described by Rev. W. 

 Kirby) deposit its eggs in the wheat-ear," etc, I notice this more 

 particularly, because the farmers in this vicinity, with scarcely an 

 exception, have fallen into the same error, and to this day suppose 

 a small black fly, of the family Muscidcn, which occurs abundantly 

 in wheat-fields, to be the real wheat-fly. 



Mr. Patrick Shirreff, of East- Lothian, gives, in the same volume 

 of Loudon's Magazine, pages 448 - 451, an excellent and very 

 accurate summary of the habits and transformations of the same 

 insect, the result chiefly of his own observations. For a concise 

 account, this is not surpassed by any that has fallen under my notice. 



Still more recently, this subject has been investigated by Prof. 

 Henslow, from whom a communication appears in the Journal of 

 the Royal Agricultural Society of England, vol. ii. p. 26 ; and in 

 the same journal for the present year (vol. vi. p. 131. plate M.) an 

 admirable production is inserted from the pen and graver of that J 

 accomplished naturalist, John Curtis, F.L.S., giving much more 

 accurate and precise descriptions and delineations of the wheat-fly, 

 in the difterent stages of its existence, than any that had previously j 

 appeared. To it I am particularly indebted for such characters as 

 enable me to say without a doubt, that the clear-winged wheat-fly | 

 of America is identical with the English Cecidomyia tritici. 



In closing this summary of the notices of the wheat-fly abroad, I 

 would allude ,to what has occurred to me as perhaps true in the 

 history of this insect, to wit, that it has somewhat regular periods 

 of recurring in such numbers as to become a pest to the agri- 

 culturist. Thus, it would appear from Mr. Gullet's account, that it 

 had been common for a few years previous to 1771. After an in- 

 terval of twenty- five years, it is again observed plentifully for three 

 or four years, and in different districts, by Messrs. Kirby, Markwick 

 and Long. Again it ceases to elicit attention, until a period but a 

 little longer elapses, when, in 1828 and the following years, it forces 

 itself once more and still more prominently into notice. All that I 

 design, is, to direct attention to this point : the facts are as yet too 

 few and too vague to justify anything more than a suggestion. The ' 



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