PROC. ENT. SOC. WASH., VOL. 24, NO. 5, MAY, 1922 111 



ducted by F. M. Webster. 1 P. hiemalis was listed by Smith 

 (22) in 1910, and the same year a brief mention of this para- 

 site as a means of control of the Hessian fly in Michigan 

 was made by R. W. Pettit (23). In 1915 a reference to 

 P. hiemalis was made by Webster (25), and in 1916 it was 

 briefly redescribed by Viereck (26). Early in the year of 

 1916, Myers (27) identified the species vernalis from the other 

 parasites of the Hessian fly which resulted in the publica- 

 tion of his original description the following year. In 1920 

 P. hiemalis was again mentioned by Walton (28). 



(Polygnotus) Platygaster vernalis Myers. 



GEOGRAPHICAL DISTRIBUTION 



This species occurs in New York, New Jersey, Pennsylvania, 

 Delaware, Maryland, Virginia, West Virginia, Michigan, Ohio, 

 Indiana and Missouri. Records so far obtained show that its 

 distribution extends as far west as Charleston, Mo., and as far 

 south as Buchanan, Va. 2 



LIFE HISTORY 



The egg is highly refractive, claviform in shape, and before 

 oviposition measures about 0.07 mm. long by 0.016 mm. wide. 

 Immediately after oviposition the main body of the egg is usually 

 found dilated to about twice the above width. A minute 

 projecting piece of membrane may sometimes be found at the 

 swollen extremity of the egg. 



The eggs are deposited singly in the eggs of the host, and some- 

 times in the newly hatched larvae before they have left the 

 exposed surface of the leaf. 



'Mr. Ainslie said that "wheat plants containing Hessian fly larvae" infested 

 with Polygnotus were transferred from Marion, Pa., to Sharpsburg, Md., and 

 that in July of the same year "ripening straw containing numerous flaxseeds" 

 was gathered and sent to Washington. The account further stated that 

 examinations ot these flaxseeds revealed the presence of Polygnotus, which was 

 thought to have proved the success of the introduction. It might be mentioned 

 that, in another review of this experiment made by Dr. Howard, (24) the 

 Polygnotus introduced were referred to as being the species hiemalis. Our 

 present knowledge of the life histories of these parasites in these localities 

 indicates that in this experiment a mistake was made in the identity of the 

 parasites used, because hiemalis does not emerge in this locality in time to 

 parasitize the summer generation of the Hessian fly. This generation of the 

 fly is, however, parasitized by "ernalis which accounts for Polygnotus beint: 

 found in the flaxseeds secured from the ripening wheat straws. 



2 The records from Michigan and Indiana were obtained from Mr. \V. H. 

 Larrimer, those from Ohio, through the kindness of Mr. Larrimer and Mr. 

 Parks, and those from Missouri from Mr. A. K. Satterthwait. 



