10 BULLETIN 766, U. S. DEPARTMENT OF AGRICULTURE. 
halfway down the posterior uterus, causing this organ to resemble 
a flat, more or less coiled ribbon, gradually enlarging toward the 
external organs of reproduction. As the developing larve are forced 
downward their axes gradually change until the axis of the posterior 
uterus and the larve is the same. (Fig. 4.) 
At the distal termination of the posterior uterus is the “laying 
organ” or larvipositor. This is slightly chitinized and has a small 
tubelike opening just large enough for the passage of one larva. 
This organ, as well as the anus, arises in the venter of the sixth 
abdominal segment and is curved forward 
when at rest, fitting into the carinate 
venter of the fifth abdominal segment. 
The larvipositor fits into a curved chiti- 
nous hook or piercer, which is grooved, re- 
resembling a V in structure. Beneath this 
hook is a supporting organ arismg from 
the fifth segment, which is strongly spined 
on both sides in such a manner that it 
reinforces the piercer while the female is 
in the act of attacking the host caterpil- 
lar. The parasite larve, as they are 
forced down the posterior uterus, are 
turned in some manner and are injected 
Fic. 3.—Compsilura concinnata: into the host, with the anterior end first. 
Reproductive system of unter’ ‘This was the conclusion the writer 
tilized female. A, Ovary, F : 
showing ovarioles; B, pairea Yeached after making a number of dis- 
oviducts; C, anterior uterus; sections of females’ after they had’ de- 
D, accessory glands; F, sper- 3 ‘ d ; 
matheee ; F, posterior uterus; posited part of their young. In these dis- 
G, rectum, showing rectal sections some of the larve were found to 
papille; H, lateral lobes of - 5 5 
dorsum of sixth abdominal be inclosed in a very thin membranous 
Sierece ee eee ig, Sheath, which fitted the body very closely, 
ndoenie segment ; J. piercer ; while others were found naked. This 
mOSe Quadaty en- leads to the inference that Compsilura 
deposits both bare and inclosed larvee. 
Pantel suggests that this might be possible on account of a prolon- 
gation of the egg stage, due to the absence of an appropriate host. 
DISCUSSION OF LARVA STAGE OF COMPSILURA CONCINNATA. 
Compsilura larvee pass their entire life within the body of the host. 
The young larva is introduced generally into the intestines, where it 
is motile, floating free until just previous to molting into the second 
stage, when it becomes attached to one of the stigmata or vesicles of 
the branching trachea. This is done by means of the three anal hooks 
