4>48 Some Account of the Wheat Fly. 



the philosophic naturalist. If we seek to find out what Hnk 

 in the chain of nature has been broken by the loss of this 

 species, what others have lost their check, and what others 

 necessarily followed the loss of that animal which alone con- 

 tributed to their support, I think we may conclude that, the 

 first being foreseen by the Omniscient Creator, at least no 

 injury will be sustained by the rest of the creation ; that man, 

 its destroyer, was probably intended to supplant it, as a check ; 

 and that the only other animals which its destruction drew 

 with it, were the intestinal worms and Pediculi peculiar to the 

 species. * 



W. Thompson, F.L.S. 

 Cork, August 10. 1828. 



Art. V. Some Account of the Wheat Fly. By Mr. Patrick 

 Shirreff, Farmer, Muiigoswells, East Lothian. 



Sir, 



Although whatever affects agriculture should be interest- 

 ing to all, yet, when submitting to the notice of the public^ 

 through the medium of the Magazine of Natural History, a 

 few observations on the habits of an insect (Cecidomyia tritACv) 

 which has been the cause of extensive injury to the wheat crops 

 in this neighbourhood for years past, it becomes me to apolo- 

 gise for entering upon a science with which I am so little con- 

 versant, and to express a hope that anxiety to advance the 

 interests of my profession, which induces me to address you, 

 will in some measure palliate the triteness of my remarks. 



Wheat flies were first observed here this season, on the 

 evening of the 21st of June; and, from the vast number then 

 seen, it is probable a few of them may have been in existence 

 some days previous. Their eggs were visible on the 23d, the 

 larva on the 30th of that month, and the pupa on the 29th of 

 July. The flies were observed depositing eggs on the 28th, 

 and finally disappeared on the 30th of July : thus having existed 

 throughout a period of 39 days. 



The flies were observed to frequent the wheat plant, only 

 including the thick-rooted couch-grass ( Ti'iticum repens), a 



* Buffon, Latham, and Gmelin have three species under the genus Didus, 

 while we find it so difficult to establish the existence of one; the evidence 

 upon which the first two of these species have been founded, viz. D. inep- 

 tus and D. solitarius, is contained in the foregoing paper, and in that of Mr. 

 Duncan, before quoted, while the third species, D. nazarenus, rests on that 

 of Cauche, whose veracity has been doubted even by his contemporaries. 

 Besides it is not likely that the three islands of the Mauritius group pos- 

 sessed each a distinct type of so singular and unique a bird 



