266 [Senate 



Ci'eatures could not have been reduced to such straits for want of the 

 appropriate repository for their eggs, until after these crops have been 

 utterly consumed. And, with the insect not exterminated, but still 

 everywhere common, now that the culture of wheat has been gradually 

 returned to with such success that it has again become general, why has 

 not the fly again increased? Why have the considerable crops of the 

 past and the abundant ones of the present year (1845) in this county, 

 been so little injured] I am firmly persuaded, therefore, that the speedy 

 diminution in the numbers of the wheat-fly, which soon follows a season 

 in which it has been extremely annoying, can not be truly assigned to 

 the cause above stated; but that it is rather to be attributed to that 

 beautiful provision of nature long since observed, and additional 

 instances of which are brought to light by the investigations of every 

 year, to wit, that an undue increase in any of the species of the anima 1 

 or vegetable world never takes place, without being speedily succeeded 

 by a corresponding increase of the natural enemies and destroyers of 

 that species, whereby it again becomes reduced to its appropriate 

 bounds. 



Whenever once introduced, it is probable the wheat-fly will ever 

 after continue in limited numbers, laying the wheat crop annually 

 Under a moderate contribution for its support. Isolated fields will 

 occur v/here its devastations will be quite serious, whilst the crop of 

 the district generally will suffer but little, and many fields none at 

 all. Such has appeared to be its history in this vicinity for several 

 years past. Seasons favorable for its multiplication will doubtless 

 occur, when its injuries will be much augmented ; as well as seasons 

 of a reverse character, when its presence will scarcely be known. It 

 is therefore very important that the entire history and habits of this 

 insect should be accurately traced out. For only with a full knowledge 

 of these, can we be able to resort intelligently to such measures as will 

 keep its numbers constantly limited, or sweep it from those fields that 

 will probably at times be excessively infested by it. 



Its habits. 



Relying upon the correctness of the published statements, that it 

 Was not till "towards the last of June" that the fly infests the wheat- 

 fields, and that the "principal deposit of eggs is made in the first 

 half of July," 1 had not commenced searching for it, when on the 



