790 
ANNUAL REPORT OF NEW YORK 
TOBACCO-WORM. PARASITE DESCRIBED. ITS WIKQS. 
epot on the middle of each, that on the third segment being large, and as 
the sutures contract in drying these spots become united. At its tip tho 
abdomen in the female is compressed and vertically truncated, with the 
sting forming a conspicuous projecting point at the lower end of the trun¬ 
cation. In the male the tip is rounded and without any projecting point, 
though when living it may sometimes be seen to protrude ‘two styles or 
slender cylindrical processes pointed at their tips, and between these a 
thicker process from the apex of which a fine bristle is occasionally thrust 
out. The legs are bright tawny yellow, becoming more dull and pale in the 
dried specimen. The hind feet and tips of the hind shanks are smoky or 
blackish. The hind thighs are also blackish at their tips and frequently 
show a dusky line along their upper sides, extending nearly to the base 
The ivings are hyaline, glassy and iridescent. The forward pair have the- 
stigma appearing as a large, opake, triangular, brownish black spot on 
their outer side slightly beyond the middle. The rib or marginal vein is thick 
and brownish black, becoming paler brown towards its base. The basal 
portion of the wing is traversed by two pale longitudinal veins, which 
are parallel, the outer one straight, the inner one curved towards its 
base. The outer vein sends off a long and nearly straight branch obliquely 
outward and backward to the anterior end of the stigma, this branch 
bounding the discoidal and the first cubital cells on their fore sides. The 
discoidal cell is triangular, with the vein on its inner side brown and angu¬ 
larly bent at one third and again at two thirds of its length, giving off at 
each of these angles a short oblique veinlet, the first one of which is brown 
and the other colorless. The first cubital cell is of the same size with the dis¬ 
coidal and is irregularly six-sided, the anterior and the inner sides being 
quite short; and the veinlet bounding this cell posteriorly is thick and 
brownish black, the inner half of its length being oblique and the outer 
half transverse, ending in the inner angle of the stigma. Beyond this, 
traversing the apical third of the wing are three longitudinal veins, which 
are very slender and colorless. The middle one of these veins is abruptly 
thickened and blackish brown for a very short distance at its base, this 
thickened portion forming, with the oblique inner end of the veinlet last 
described, two of the sides of the small triangular cellule which is common 
in the wings of the insects of this genus and family, but the short veinlet 
which should complete the inclosure of this cellule on its hind side, is wholly 
wanting. 
Mr. Say is wholly silent respecting the interesting habits of this insect, 
merely remarking that he obtained eighty-four of the flies from the larva 
of a Sphinx in the month of June. As I have had the flies come from the 
cocoons in July and also in September, it is probable that they are abroad 
upon the wing during the whole summer season, actively searching for 
suitable worms to inoculate with their eggs. As will be seen from a state¬ 
ment in one of the following pages, this parasite does not appear to be 
limited to the tobacco-worm, but preys upon the larvae of other species of 
Sphinx also. And some of our other species of Microgaster have the same 
habit of fastening their cocoons to the larvae from which they respectively 
