SERPHOID AND CHALCIDOID PARASITES OF THE HESSIAX FLY 25 



HOSTS AND LIFE HISTORY 



Trichacis rernadus is a primary, solitary, internal parasite of the 

 hessian fly. It is also said to attack Mayetiola a venae Marchal in 

 France and J/, phalaris Barnes in Pomerania, Germany. 



According to Marchal, who has written extensively on the post- 

 embryonic development of this species, oviposition takes place in 

 May and June in the Department of Vendee, France. While he has 

 not observed the act of oviposition, he has always found the larva 

 of the Platygaster in the very young larva of the host soon after its 

 emergence from the egg, and he therefore concludes that the parasite 

 egg is deposited either in the egg of the host or else in the host larva 

 just after it emerges. The first-stage parasite larva is always located 

 in the nervous system of the host. Although Marchal observed as 

 many as four first-stage larvae of the parasite in a single host larva, 

 he never found more than one second-stage larva per host. He ob- 

 served three larval stages. The parasite pupates in the puparium 

 of its host. 



There is probably a single generation of the parasite per year and 

 emergence takes place in the early spring. 



DISTRIBUTION 



This species has never been found in North America and, in view 

 of the extensive investigations of parasites of the hessian fly that 

 have been carried on in this country, it is safe to say that it does not 

 occur here. In Europe it appears from the records to be a common 

 and widely distributed species. It has been recorded from England, 

 France. Germany, and from several of the governments of Kussia. 

 It probably occurs throughout the European range of its host. 



IMPORTANCE 



No data are available upon which to base an estimate of the im- 

 portance of the species in the control of the hessian fly. The fact 

 that it usually has been reared wherever the parasites of the fly have 

 been studied in Europe indicates that it is a more or less constant 

 factor, but it is probably of less importance than several of the other 

 parasites. 



Superfamily CHALCIDOIDEA 



Family CALLIMOMIDAE 



DITROPINOTUS AUREOVIRIDIS Crawford 

 (Fig. 6) 



Ditropinotus aureoviridis Crawford, Jour. N.Y. Ent. Soc. 15: 178, 1907; Web- 

 ster, U.S. Dept. Agr. Yearbook 1907:255, fig. 20, 190S ; Bur. Ent. Circ. (rev.) 

 66 : 4, 1908 ; Houser. Ohio Agr. Expt. Sta. Bui. 226 : 196. 1911 ; Phillips. Jour. 

 Econ. Ent. 10 : 145, 1917 ; U.S. Dept. Agr. Farmers' Bui. 1006 : 13, 1918 ; Loch- 

 head, Class book of economic entomology . . ., p. 354, 1919; Gahan, Ent. Soc. 

 Wash. Proc. 22: 236, 1920: Pettit and McDaniel, Mich. State Bd. Agr. Rpt. 

 (1918/19) 58: 275. fig., 1920; Phillips and Poos, Jour. Agr. Research 21: 408, 

 figs. 2 and 3, 1921 : U.S. Dept. Agr. Farmers' Bui. 1323 : 8, 1923 : Parker. Ann. 

 Soc. Ent. France 93: 2S2, 1924; Phillips, Jour. Agr. Research 34: 751. 1927; 

 Leonard. N.Y. (Cornell) Agr. Expt. Sta. Mem. 101: 975, 192S : Hill and Smith, 

 Jour. Agr. Research 36 : 153, 1928 ; Larrimer, Jour. Econ. Ent. 24 : 653, 1931. 



Ditropinotus flavicoxus Gahan, Ent. Soc. Wash. Proc. 14: 5, 1912. 



