HYMENOrTERA. 
r r 
000 
leaf, but that, in many cases, it was seated in the joint 
itself, the whole substance of which became enlarged and 
distorted. In a smaller number of cases, it was found to 
occupy the culm or stem, above the joint, which was 
swollen so as to form an irregular gall-like tumor, while 
the leaf-sheath remained unaffected. These woody tumors 
had several little cells in them, varying in number from 
six to ten or more ; and every cell contained an insect, 
in the pupa or chrysalis state. The samples of straw 
reserved for myself were put into a small glass jar, to 
secure the insects when they had completed their transfor- 
mations. Early in May, winged insects began to perfo- 
rate the tumors and come forth, and they continued to 
issue during ten days or more. Their appearance was 
probably hastened by the jar being kept in the house, in- 
stead of being exposed to the air abroad. 
These insects so nearly resemble, in form, size, and color, 
the Eurytoma formerly obtained from the barley-straw, that 
1 am persuaded they are at least mere varieties of the 
same species, if not absolutely identical. The only ap- 
parent difference between them consists in the color of the 
fore shanks ; these, in the wheat-insects, being pale yellow, 
and faintly tinged with black only on the outer edges, in 
a few individuals. Among fifteen specimens only one male 
was found, and this did not appear till the month of June. 
Dr. Fitch obtained from his samples of straw above one 
hundred specimens of the same kind of Eurytoma , and all 
of them females. Among; them he found another dial- 
cidian insect, a species of Pteromalus, probably a parasite 
of the Eurytoma , and has favored me with a description 
of it. The head and thorax are of a dark metallic green 
color; the abdomen is slightly depressed, polished, purplish 
black above, bright copper-colored beneath. The antennas 
are black, except the basal joint, which is of a brilliant 
copper-color. The thighs are pale yellow ; the shanks and 
feet blackish, the hind pair with a broad pale ring around 
