104 Ohfervations on the Hejfian Fly. 



great a variety in the transformations of this infe61, that it. may- 

 be found in all its different ftates, at all times in the year, 

 excepting in the cold weather, or in tlie fpring. From what 

 has been before obrerved on this fubjecl, it appears, that this 

 opinion may very probably be true, fo far as it refpecls the 

 month of September, and a part of Oclober, and pofTibly with 

 refpeft to the latter part of May, if the fly, which is hatched 

 in the fpring, fliould continue until that time; but cannot be 

 applied with propriety to June and July, in which months I 

 have fuppofed that the infetl does not exift in the (late of a fly. 

 It is probable that this opinion may have arifen from thefe 

 circumftances ; that there are feveral fpecies of gnats, ar flies, 

 which may very eafily be miftaken for the HeflGian fly ; and 

 that in examining wheat, to difcover whether the infetl is 

 transformed into a fly, it is very diflRcult to difl;inguifli the 

 fhells of the chryfalis v/hich has lain in the wheat during the 

 winter, from thofe of the next generation which has fucceeded 

 them in the fpring and fummer following ; and this latter cir- 

 cumfl;ance, without great care, will be a fource of perpetual 

 miftake and error to thofe who may examine into the nature 

 of the infeft, and is perhaps one of the greatefl obftacies to . 

 arriving at certainty on this fubjeci. 



Of all the various methods which have been propofed to 

 the public, for preventing the injurious efifefts of this infcft, 

 that of raifmg the different forts of bearded wheat has befl 

 fucceeded. This kind of wheat having a more folid fl;raw than 



