SERPHOID AND CHALCIDOID PARASITES OF THE HESSIAN FLY 139 



Jour. Agr. Research 36: 153, 1928; Wehrle, N.Y. (Cornell) Agr. Expt. Sta. Bui. 

 481 : 29, 1929. 



Tetrastich us rileyi Lindeinan. Eul. Soc. Nat. Moscou (2) 1: 183, 1887; 

 Orinerod, Entomologist 20: 317, 1887; Riley. U.S.Dept.Agr., Div. Ent, Insect 

 Life 1: 132, 1S88 : Meyer. Rpt. Appl. Ent. Leningrad 4: 241, 1929; Blunck, 

 Ztschr. Angew. Ent. 18: 589, 1931. 



Tetrastich us sp, Washburn. Minn. State Ent. Bui. 77: 7, 1902; Ainslie, Ent. 

 Soc. Wash. Proc. 10: 15, 1908. 



DESCRIPTION 



Tetrastichus carhwtus differs from all other parasites said to attack 

 the hessian fly except T. prodv.ctus Riley and ainsliei Gahan. bv the 



Figure 32. — Tetrastichus carinatus Forbes: A, Adult female: B, antenna of female 

 C, antenna of male. A, x 24. 



two parallel grooved lines running from the base to the apex of the 

 scutellum. From T. productus it may be distinguished by the 

 broader, shorter, and less conical abdomen, by the less strongly 

 sculptured propodeum, and by the usually paler femora. 



Female. — Length 0.8 to 2 mm. Head transverse, concave in front (fre- 

 quently collapsed); occiput slightly concave; ocelli in a low triangle, lateral 

 ocellus about twice its own diameter from the eye margin ; eyes very nearly 

 bare, extending to the back of head, the temples absent ; malar space equal 

 to nearly half the eye height ; frons deeply and broadly depressed, with a median 



