36 THE HESSIAN FLY IN THE UNITED STATES. 
Habitat. — Western States. 
This species seems to have been first reared by Dr. Riley from specimens of the 
Hessian fly (Cecidomyia destructor Say) August 16, 1876, received from Blair, Nebr. 
It has, however, since been bred from the same fly by various persons in the Western 
States. Professor Forbes reared it in 1888 at Champaign, 111. ; Professor Cook, of the 
Agricultural College of Michigan, in 1890, and Professor Webster, at Laporte, Intl., 
in 1889. 
I know of no specimens reared in the Eastern States. Can it be a species moving 
eastward? (Ashmead.) 
Lygoccrus triticum Taylor. 
Ceraphron triticum Taylor, Am. Agric. 1860, p. 300, f. 1 ; Cress. Syn. Hym., p. 248. 
Lygocerus triticum Taylor, Ashmead, N. Am. Proctotrypida?, p. 110. 
This fly does not correspond with the above (Ceraphron destructor Say), therefore 
1 have named it triticum, from the botanical name of wheat. It is not of such a 
shining black as Mr. Say's fly, but is rather rusty in appearance, from a few hairs 
scattered over its body. In some specimens, when very fresh, the legs have a bright 
tinge of yellow. The antenna? (&, fig. 2) are termed setigerous (having the basal 
joint large) and the last four globular, the intermediate one furnished with four 
long bristles resembling plumes. This is a very sure mark for distinguishing this 
family according to European classification. The eyes are large in proportion, the 
palpi 3-jointed. The fore wings have submarginal cells, with a faint nervure ran 
ning to apex. The under wings have a long nervure running through and two 
smaller ones descending to the inferior region; these are so very slight that you can 
only see their existence by a deep shade of the wings in a strong light, but are evi- 
dently nervures, indistinct as they are. The ovipositor is retractile and tubular. 
The fly deposits her eggs in the pupa of the Hessian fly. (Taylor.) 
Unknown to me, and the above description is copied from the American Agricul- 
turist. Miss Taylor further informs us that "this fly can be found in every wheat 
field throughout the country, from spring to autumn." Her description is very 
imperfect, and her figure of the male antenna strongly recalls the branched antenna 
of an Eulophus. (Ashmead.) 
The above reference, quoted from Ashmead's "Proctotrypidse," gives 
all that appears to be known concerning- this species. 
SECONDARY PARASITES. 
Aside from the parasites attacking the Hessian fly directly, there are 
species which attack their parasites and are called secondary parasites. 
These, of coarse, by reducing the numbers of the primary parasites, 
operate to the disadvantage of the cultivator. Two species have been 
described in this country, both in the genus Tetrastichus. 
Tetrastichus productus Riley. (Fig. 7.) 
Male. — Average length, 1.5 mm. ; wing expanse, 2.6 mm. ; greatest width of the 
fore wing, 0.5 mm. Scape somewhat broadened below, inserted near the middle of 
the face in a deep groove, and reaches nearly to the ocelli. Elagellum long, flat- 
tened, hairy, each joint except club with a whorl of long, slender hairs at base. 
Funicle joints twice as long as wide. Head considerably shrunken after death. 
Head, pronotum, and mesonotum smooth and shining; metanotum, pro, meso, and 
meta pleura, and all coxre above finely punctate. Submarginal vein of the fore wing 
with a single stout superior bristle behind its middle; marginal vein three times as 
