1885.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 413 



ON THE PARASITES Or THE HESSIAN FLY. 

 BV C. V. RII<X:Y, Ph. ]>. 



Considering the number of articles that have been written npon the 

 Hessian Fly {Cccidomyia destructor), very little of a critical and exact 

 nature has been publislied concerning its parasites. 



But two species have hitherto been described with any detail, although 

 two others are mentioned by Herrick without identification, and without 

 description sufficient to render them recognizable. In Europe the same 

 uncertainty seems to exist. Even Dr. Balthazar Wagner, in his admi- 

 rable paper,* gives very little that is definite concerning the parasites, 

 and although he states that he sent specimens to Dr. Foerster, I am 

 unable to (ind that tbi.-; celebrated hymenopterist ever named them. 

 The advantage of correct knowledge as to the habits of these parasites, 

 and of being able to refer to them definitely, is apj^arent when we con- 

 sider the importance of their host, which was conspicuous for its ravages 

 on the wheat of ISTew England in pre revolutionary times and has re- 

 cently crossed the Rocky Mountain range so as to threaten the wheat 

 of the Pacific. During the past few years I have made a special study » 

 of these parasites, and will consider five of them in what seems to be 

 the order of their importance. The figures accompanying this paper 

 were prepared at the Department of Agriculture and are used here with 

 the kind permission of Commissi(mer Colman. 



Merisus destructor (Say). 



[Plate XXI, fig. 1]. 



SYNONYMY. 



Cerapliron destructor Say. Jourual of the Academy of Natural Sciences of Phila- 

 delphia, vol. i, No. 3, pp. 45-48, read Judc 24, 1817. Say's Complete Writings, 

 Le Conte edition, vol. ii, p. 6. 



Eurytoma destructor (Say). Harris, a report on the insects of Massachusetts inju- 

 rious to vegetation. Cambridge, 1S41, p. 432. 



"Owe of the liiilophides." Westwood, Introduction to the Modern Classification of 

 Insects. Loudon, 1840, vol. ii, p. 160. 



Pteromelas destructor (Say). Curtis. Journal of the Royal Agricultural Society. 

 London, 1846, vol vi., p. 139. 



Eaphitelus, or Stortliygocerus destructor (Say). Harris, op. dt., 2ded. Boston, 1852, p. 586. 



Semiotellus destructor {Sny). Fitch. Seventh report on the noxious, beneficial, and 

 other insects of the State of New York. Transactions of the State Agricult- 

 ural Society for 18G1. Albany, 1862, p. 827. 



It will be seen from this synonymical list that there has been much 

 difficulty in properly placing this insect. Since Fitch placed it in the 

 genus Semiotellus it has remained undisturbed, but in view of Thomson's 

 recent studies of the Pteromalinae it is necessary to transfer destructor 

 to his genus Merisus. 



* Untersuchuugeu ueberdieneue Getreidegallmiicke. Fulda, 186L Translated by 

 Dr. Carl Gissler, it api>ears as an appendix to the Third Report of the United States 

 Entomological Commission, p. [8]. Washington, 1883. 



