72 PRIZE ESSAY: 



election of varieties which can be sown so late as to escape the 

 May attack of the Hessian fly, the June and July attack of the 

 midge and rust will cover all contingencies. Can this be accom- 

 plished ? Have we such a variety of wheat as will satisfy 

 these conditions ? The late lamented Mr. Wade, of Cobourg, 

 recommends the ' Fife Wheat,' which is described in paragraph 

 161. The ' Fife Wheat,' or as it is called in the Townships east 

 of Lake Simcoe, Scotch wheat, is there a great favorite. It is not 

 ( liable to rust,' may be safely sown much later than many other 

 varieties, and it is at the same time very productive. For addi- 

 tional notice of the Fife Wheat, see paragraph 161. 



THE CAUSE OF THE SPREAD OF THE HESSIAN FLY. 



127- A point of interest in the history of this insect is the 

 stated apparent periodical character of its visits. A little reflec- 

 tion will show that this seeming regularity may be attributed to 

 causes which are independent of one another, but yet have an 

 important bearing upon its multiplication or diminution. The 

 first and probably the most influential relates to the general 

 wide spread cultivation of its favourite food ; the second to the 

 favourable meteorological conditions of the season : these stimu- 

 late and encourage its increase ; the third affects the diminution 

 of its numbers, and involves the excessive multiplication of the 

 parasites which prey upon it. 



128. Under the article * Wheat Midge/ paragraphs 158-9, a 

 much more apparent periodicity is observable in the successive 

 appearances of that insect. The following notices of the exces- 

 sive appearance of certain insects in the United States and Ca- 

 nada, with the character of the season during and immediately 

 preceding their visit may prove interesting. They are not ad- 

 vanced with any expectation that a near approach to a clue to 

 the cause of the greater or less distribution of the Hessian fly 



