LIFE HISTORIES AND METHODS OF REARING 

 HESSIAN-FLY PARASITES 



By C. M. Packard,^ 

 Scientific Assistant, Cereal and Forage Insect Investigations, Bureau of Entomology 



INTRODUCTION 



The most effective factors in the control of the Hessian fly {Mayetiola 

 destriictor Say) in the past have been its parasites. There are seasons, 

 however, when the parasites become scarce and the Hessian fly exceed- 

 ingly abundant. Again, in the same season the Hessian fly seems prac- 

 tically free from parasites in some localities while in others its parasites 

 are numerous. A thorough knowledge of the life histories, field habits, 

 relative efficiency, and effective methods of artificial propagation and dis- 

 semination of the different parasites, therefore, might make it practicable 

 to introduce the most efficient species from localities where they are 

 abundant into other localities where the host is working destruction 

 unchecked by its enemies. It might also be possible to propagate arti- 

 ficially and to disseminate the parasites during periods when they have 

 become scarce in the fields, and thereby shorten the period of destructive 

 abundance of the Hessian fly. Up to the present time very little accurate 

 and detailed information seems to have been recorded regarding the life 

 stages, habits, and efficiency of Hessian-fly parasites. It has been uncer 

 tain whether or not some of the species involved were true parasites. 

 Some results in this direction have been accomplished by the author 

 during the last two seasons, and the purpose of this paper is to make 

 public these results arid the methods used in attaining them. 



The life histories and methods of rearing three hymenopterous parasites 

 are treated in this paper: Eupelmus allynii French, Merisus destructor Say, 

 and {Merisus) Micromelus subapterus Riley. The seasonal history and field 

 habits of these parasites wall require another season's observation before 

 they can be effectively treated. The scope of this paper is therefore 

 limited to the life histories and relationships of these species to one another 

 and to their common host as determined under laboratory conditions. 



' The writer wishes to acknowledge his indebtedness to ^lessrs. E. O. G. Kelly, W. R. Walton, A. B. 

 Gahan, W. R. McConncll, and J. A. Hyslop, all of the Bureau of Entomology, for helpful advice; to Mr. 

 Kelly for making the work possible, and to Mr. Gahan for determining all specimens. 



Journal of Agricultural Research, Vol. VI, No. lo 



Dcpt. of Agriculture, Washington, D. C. June 5, 1916 



dv K— 34 



(367) 



