254 QUARTERLY JOURNAL. 



account for this only by supposing that these heads were just be- 

 ginning to be protruded from their sheaths as the operations of the 

 fiy were closing for that year ; and hence confidently inferred that 

 if that wheal had been sowed a 'few days later, it would have es- 

 caped entirely, or a few days earlier, it would have been entirely 

 destroyed. By a reference to my Farm Book, I find this crop was 

 sowed April 26th, and cradled August lOlh, but no note was taken 

 of the time when it was in blossom. I must confess, however, that 

 my observations the present season have greatly diminished my 

 confidence in the time of sowing as securing the crop from injury. 

 Though I did not see ihe fly abroad until the 16lh of June, it was 

 then present in such swarms, and had already deposited its eggs so 

 profusely, that I think it must have commenced appearing quite 

 early in that month. It, moreover, continued to be abundant, until 

 about the middle of July, and specimens were occasionally met 

 with a month longer. Certainly if it is usual for it to be spread out 

 over such an extent of time, it will be vain to rely upon the time of 

 sowing, to insure a crop against its ravages. Some observations in 

 the foreign accounts also throw light upon this subject. Mr. ShirrefF 

 says, in 1829 the fly appeared June 21 si; "and from the vast numbers 

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

 existence some days previous." Their eggs were seen June 23d, and 

 must therefore have been deposited on the evening of the 22d. " The 

 flies were observed depositing eggs on the 28lh, and finally disap- 

 peared on the 30th of July, thus having existed through a period of 

 thirty-nine days," and depositing eggs during thirty-seven of these 

 days, I know not how Mr. S. could be certain that the fly had dis- 

 appeared for the season on the 30th of July, for his account is 

 dated the first day of August. For a few days only after their first 

 appearance, he tells us, they frequented the couch-grass as well as 

 the wheat. Was not this because there was not at that time a suffi- 

 cient quantity of wheat in bloom to accommodate the number of! 

 insects that were then out ? And Mr. Markwick distinctly states 

 that it was after the grain had been harvested, that he found thti 

 larva3 in the wild oats. Were not the parent flies then obliged to 

 resort to this plant, because all the wheat had become mature ere 

 they had completed depositing their eggs ? These facts certainly 

 make it appear as though the fly is often abroad before the wheat 

 commences blossoming, and continues till after it becomes mature. 



