46 MISC. PUBLICATION 17 4, U.S. DEPT. OF AGRICULTURE 



From this list of hosts it is apparent that Eupelmus allynii is 

 capable of developing under a variety of circumstances. That it 

 may be either a primary or a secondary parasite is established beyond 

 doubt. Just what its true relation to some of these hosts may be, 

 is not definitely known, but in the cases of the hessian fly and the 

 species of Harmolita it is almost certainly more often primary than 

 secondary, the degree of secondary parasitization depending largely 

 on the abundance or scarcity of competing species at the time the 

 Eupelmus is ovipositing. If the particular host chosen by the Eupel- 

 mus happens to be already occupied by some other species of para- 

 site, or even by one of its own species, it will develop at the expense of 

 the earlier occupant. There is no evidence, however, to indicate that 

 the Eupelmus discriminates between parasitized and unparasitized 

 hosts when ovipositing. 



The species is normally a primary, external, solitary parasite of 

 the hessian fly. According to Packard, the egg is deposited in the 

 flaxseed but external to the fly larva or pupa. The parasite feeds 

 externally upon its host and normally passes through five instars. 

 Pupation is accomplished as a naked pupa within the host puparium, 

 emergence taking place through a hole gnawed by the adult. The 

 seasonal history of the species was not worked out by Packard, but 

 according to Phillips and Poos, who studied its biology as a parasite 

 of jointworms, it overwinters as a full-grown larva in the joint worm 

 cells in old wheat stubble, the adults appearing in April and May 

 in the latitude of Virginia, and four generations were reared in the 

 laboratory during one breeding season under conditions as nearly 

 normal as it was possible to keep them. 



DISTRIBUTION 



This species apparently occurs generally throughout the wheat- 

 growing region of the United States. It also occurs in Canada, hav- 

 ing been recorded from Prince Edward Island by Fletcher, and from 

 Manitoba by Criddle, while specimens from Ontario have been seen 

 by the writer. No doubt it is present throughout the entire wheat- 

 growing region of North America, and it may occur in regions where 

 wheat is not grown but where wild grasses infested by jointworms 

 or other hosts are present. 



Apparently it does not occur in Europe. 



IMPORTANCE 



Hill and Smith rank Eupelmus allynii as the most important 

 chalcidoid parasite of the fly in the Eastern States, it being out- 

 ranked only by the serphoids Platyg aster zosine (syn., vernalis) and 

 P. hiemalis. Packard found it to rank third in importance in Cali- 

 fornia, while L. P. Kockwood estimates it as ranking fourth among 

 parasites of the fly in Oregon. 



EUPELMUS ATROPURPUREUS Dalman 



(Fig. 11) 



Eupelmus atropurpureus Dalman, Svenska Vetensk.-Akad. Handl. 41: 381, 

 1820; Nees von Esenbeck. Hymenopterorum ichneumonibus affinium mono- 

 graphiae . . ., v. 2, p. 78, 1834 ; Ashmead, Psyche 8 : 137. 1897 ; Marchal, Ann. 

 Soc. Ent. France 66: 93, 1897; Dalla Torre, Catalogus hymenopterorum . . ., 



