Ohfervaticns on the Hejfian Fly. . loi 



going account, that nature appears to have fixt this transfor- 

 mation to commence with, and continue through the whole of 

 that feafon of the year, which is moft proper for fowing wheat. 



' The fly is the third and laft flate of the infeft, and com- 



pleats what I have here termed one generation. It very much 

 refembles the mofchetto, except that it is much Imaller and 

 has a fliort bill. I never could difcover that it preyed upon 

 the wheat, and very probable it requires no other nourifhment 

 than what it may obtain from dew or moifture. It is of a 

 texture fo delicate, as to be injured or deftroyed by the flighted 

 accident. Soon after it becomes a fly, it again lays the maggot 

 on the wheat fown in the fall ; and if this is not up at the parti- 

 cular time the fly requires it, the maggot muft be in great 

 meafure loft, and the fpecies reduced to a fmall number. It is 

 difficult to difcover for what length of time the infeft will con- 

 tinue a fly in its natural fituation in the field : in all iiaftances 

 where it has been hatched under cover, or in glaffes provided 

 for thatpurpofe, it has foon periflied ; and if wx may reafon by 

 way of analogy from the cafe of other infe6ls, there is little 

 reafon to doubt, but that the time of its continuance muft be 

 very fliort. The maggot generally proves more deftruclive 

 to wheat in the fall of the year than in the fpring ; and before 

 cold weather is transformed into a chryfalis, in which ftate it is 

 prepared to remain during the winter, and in the fpring will 

 again be transformed into a fly ; which compleats two genera- 

 tions of the infect in one year. 



