194 



Fig. 237.— Tlie Hessian fly and its transformations. 

 A healthystalk of wheat on the left, the one on the right dwarfed and the lower 

 leaves beginning ti> wither and turn yellow; the stein swollen at three places, 

 near the ground where t he flaxseed Ui) are situated, between the stem and 

 sheathing-base of the leaf. a, egg of the Hessian fly (greatly enlarged, as are 

 all the figures except <• and )i); b, the larva, enlarged, the line by the side, in 

 this and other figures, showing the natural length; c. the flaxseed, puparium, 

 <>r pupa-case; d, the pupa or chrysalis: e, the Hessian fly, natural size, laying 

 its eggs in the creases of the leaf; /. female Hessian fly, much enlarged: fir, 

 male Hessian fly, much enlarged; h. flaxseed between the leaves and stalk; 

 i, Uhalcid parasite of the Hessian fly, male, enlarged.— Fig. b drawn by Mr. 

 Riley ; Fig. d by Mr. Burgess; Figs, a, c,and i, by the author; h, ;/, /, drawn on 

 wood by Li. Trouvelot. (To face page 195.> 



