WHEAT MOW FLY DESCRIPTION, AND ITS PARASITE. 303 



white color, and rather larger. Their transformations are like 

 those of flies generally, the outer skin of the larva or maggot 

 contracting and becoming dry and hard, and forming the case 

 within which the insect lies in its pupa state. When the larva 

 skin of this species is thus dried, with the pupa reposing within 

 it, it appears as represented, plate 2, fig. 2, 2 a being a highly 

 magnified view of its upper and 2 b of its under side. It is but 

 the tenth of an inch long, and 0.03 in diameter; it is shining and 

 of a pale yellow color, of an oval or rather an elliptical form, 

 more rounded at the head and pointed at the opposite end, the 

 segments distinctly marked by transverse constrictions. 



These flies appear much like the common house fly, reduced to 

 an infantile size. I supposed they would prove to be one of the 

 European species of Oscinis, until I came to examine them, 

 when I found that, though they belong to the group Oscinides, 

 they are generically distinct from both Chlorops and Oscinis, in 

 having bristles or hairs upon the face as well as upon the crown, 

 and in having the two little transverse veinlets of the wings sita- 

 ated quite near the base. They thus pertain to the genus JJgromyza 

 a name meaning field flies, as this genus is characterised by Mac- 

 quart, and to his section AAA, and to his subsection DDD, but 

 they are clearly distinct from either of the species which he de- 

 scribes; nor am I aware that any of the members of this exten- 

 sive genus have hitherto been noticed as depredators upon wheat, 

 like their kindred of the genera Chlorops and Oscinis. The 

 present species may therefore be designated 



The wheat mow fly, dgromyza Tritici, (plate 2, fig. 1.) It is 0.08 in length, 

 and to the tip of the closed wings 0.11. It is black, with a broad pale reddish yel- 

 low band upon the front above the base of the antennas, and the mouth broadly 

 margined with dull yellow. The legs are brownish black, the knees slightly marked 

 with pale yellow. The wings are notched on their outer margin near the base, at 

 the apex of the first vein. The veinlets are situated near the base of the wing and 

 near each other ; and the inner middle vein is not prolonged beyond the second 

 veinlet. 



In the same box in which these flies were hatched was found 

 four individuals of a parasitic fly which had evidently come from 

 some of the worms of the wheat mow fly. They pertain to the 

 Family Proctrotrupid^e of the Order Hymenoptera, and to the 

 genus Diapria. They may therefore be named 



The wheat siow fly's parasite, Diapria Jlgromyzce. They measure 0.06 in 

 length, and to the tip of the closed wings 0.08. They are black and shining, with shanks 



