15^ dhfervations on the Hejfian Fly. 



perhaps be afFe6led by bad weather and unfavorable winds, 

 which may benumb the fly and prevent it from taking its flight. 

 It is fuppofed that the fly in its progrefs from one place to 

 another, and on fields of wheat, is inclined to keep in fmall 

 fwarms ; and this opinion appears probable from this circum- 

 ftance, that fome fields of wheat are frequently much more 

 injured than others which are not far difl;ant, and the fame field 

 is frequently injured in fmall patches whilft other parts appear 

 in fome meafure to have efcaped. The maggot is properly the 

 firft ttate, or mode of exiftence, with the infeft ; for although it 

 appears, at firft, to refemble an egg, yet I am inclined to believe 

 that the fly is viviparous, for I never could difcover that any 

 transformation took place, from an egg to a maggot. It is 

 always found between the loweft part of the leaf of the wheat, 

 and the part which forms the main ftalk or ftraw, to the latter 

 of which it clofely adheres ; and is generally within the outfide 

 leaf, fo as to lie as near the root as poflible ; but to this there 

 are fome few exceptions ; for it is fometimes, though very 

 rarely, to be found a litde above the upper joints ; but inftances 

 of its being very far from the root are fo rare, that I never could 

 find but one or two which lay above the highefl; joint. It 

 refembles at firft a very fmall white nit, and as it grows larger, 

 becomes a fluggifli, and almoft inanimate maggot, of a white 

 colour, and capable of very little perceivable motion. In this 

 ftatc, the proper and moft natural food of the infe6l, is the fap 

 or juice of that kind of green wheat which has the moft delicate 



