EXPLANATION OF PLATES. 
Plate I. 
A wheat plant showing an uninjured stalk at left and one infested with Hessian fly 
at right, the latter dwarfed, leaves withered, and stem swollen at three points near 
the ground, where the "flaxseeds" are located, between the leaf-sheath and stem. 
a. Egg of Hessian fly, 9 greatly enlarged, as are all figures except e and h. 
h. The larva — enlarged, the line by the side showing natural length. 
c. The pupariuin, "flaxseed," or pupa case. 
d. The pupa or chrysalis. 
e. Adult female, natural size, ovipositing. 
/. Adult female — much enlarged. 
g. Male — much enlarged. 
h. "Flaxseed'' in position between leaf-sheath and stalk. 
i. Parasite Merisus destructor, male — enlarged. 
From Packard, Third Report U. S. Entomological Commission; b, drawn by Dr. 
Eiley; d and / by Mr. Burgess; a, g, c, i by Packard. 
Plate II. 
Fig. A. Side view of the female — greatly enlarged: a, three joints taken from the 
middle of antenna of female; a', the three terminal antennal joints; a", 
the four basal; and a'", the two terminal male antennal joints; b, a max- 
illary palpus; c, scales from body and wings; d, e, side and vertical view 
of the last joint of the foot, showing the claws and footpad or pulvillus 
between them, and the scales on the joint. Drawn by E. Burgess. 
B. Larva magnified, with the breastbone in the second next ring to the head; 
Ba, the breastbone highly magnified; Bb, head from beneath, enlarged; 
Be, larval spiracle and its tubercle and trachea leading from the spiracle. 
B drawn by Dr. Riley; Ba, Bb, Be by Mr. Burgess. 
C. Side and front view of the pupa or chrysalis. Drawn by Burgess. The 
abdomen of the side view is rather long, as the insect when drawn was 
just emerging from the semipupal stage, which it assumed December 1st. 
D. The "flaxseed," 7 puparium or pupal case. The line by the side of the com- 
plete figures denotes the natural length of the insect. Plate II is from 
Packard, Third Report IT. S. Entomological Commission. 
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