Oct. 23, I916 
Life History of Habrocytus Medicaginis 
149 
the ring-joints, about equal; following funicle joints a little longer than the first and 
a trifle longer than broad; viewed from in front the head is broader than long, the 
clypeal region with converging strise and a deep median sinus on the anterior margin; 
viewed from above the head is slightly broader than the thorax, narrow antero- 
posteriorly, the occiput slightly concave, the ocellocular line longer than the lateral 
ocellar line, the lateral ocellar line not equal to half the postocellar line; pronotum 
strongly transverse with a sharp margin anteriorly; propodeum short, without a neck, 
with a median carina and lateral folds, the region between the lateral folds more or 
less distinctly wrinkled and with a fovea-like depression at the base and another at 
the apex of the fold; the region outside the lateral folds is usually more faintly sculp¬ 
tured with indistinct lines; propodeal spiracles elliptical; marginal and postmarginal 
veins subequal, the stigmal one-third shorter; abdomen conic-ovate, about as long as 
the head and thorax and nearly smooth, the dorsal segments beyond the first with 
very faint transverse lines. Head and thorax aeneous; antennae brown, the scape 
slightly paler beneath; wings hyaline; all coxae aeneous like the thorax, all tro¬ 
chanters and femora black with an aeneous tinge; tibiae and tarsi usually reddish 
yellow, the former often brownish except at apex; apical joint of all tarsi dark; abdo¬ 
men polished aeneous. 
LIFE HISTORY OF THE HOST 
The host insect (B. funebris) of H. medicaginis completes its entire 
life development within the growing seeds of alfalfa, red clover (Trifo¬ 
lium incarnatum), and wild species of Medicago. After reaching matu¬ 
rity the adult eats a hole through the seed wall and through the wall of 
the seed pod to make its escape. B. funebris may pass through from 
one to four or five generations in a single season. 
METHOD OF STUDYING THE PARASITE 
The fact that H . medicaginis completed its entire development within 
the unbroken walls of an alfalfa seed made it necessary for the writer to 
dissect many seeds under a microscope and remove this parasite in its 
different Stages for special study. Small parasite larvae removed from 
seeds were placed singly upon a larva of their host. The host and para¬ 
site were then placed in a small cavity made in a 7-mm. cork and covered 
by a glass vial (PI. 4, fig. B). A most satisfactory method of observing 
one of these larvae in its development was to place it upon a larva of 
B. funebris and keep both host and its parasite in a cavity made between 
two layers of sheet cork. The upper layer of cork could then be removed 
to expose the parasite larva. 
STAGES OF HOST SHOWING PARASITISM 
H . medicaginis is parasitic upon the larval stage of its host with 
possibly a few exceptions. Microscopic dissections of many infested 
alfalfa seeds showed 77 larvae of this species, each feeding externally upon 
the larval stage of its host (PI. 4, fig. D). This parasite was in no case 
found to be attacking the pupa of B. funebris . Only a single parasite is 
able to develop upon its host within the walls of a single infested alfalfa 
seed. 
