DIPTERA. — 99 
and thus give a very secure attachment. The egg is narrow, ovoid, broadest at its 
middle, and larger at the base than at the tip, which is more or less abruptly and 
obliquely truncate (fig. 43d). 
The striking results of the researches of Dr. Curtice, which showed 
that the larve are taken into the mouths of the animals and pass by 
way of the cesophagus to the subcutaneous tissue along the back, have 
already been mentioned, and it now remains to give in detail the stages 
of the larva during this strange career. The time occupied by the 
larva is sometimes quite long, occupying several months in reaching 
the skin, while the development after reaching this location is more 
rapid. 
va Sept ch ie 
yese° Ea 
enter 
tT ft 
RS See 
oe 
ett ietee 
a 
Fic. 43.—Hypoderma lineata: a, eggs attached to hair; b, ¢, d, dorsal, ventral, and lateral view of 
egg; e, embryonic or first larva, as seen in the egg; /, g, mouth-parts of same—enlarged; fh, anal seg- 
ments of same—still more enlarged (from Insect Life). 
The larva, first stage.—This stage (fig. 43,e) when ready to leave the egg, or when 
first hatched, is 0.08 mm. long by 0.02 mm. in width, tapering above. Within the 
egg it fills the cavity and may be seen through the shell and quite readily removed. 
It is dull white in color, with the surface from the second to the twelfth joints dis- 
tinctly and densely spinose. The armed area occupies the entire surface of these 
joints, except a narrow lateral free space. The arrangement of the spines on these 
joints, except the last, is uniform, with perhaps a slight increase in the size of the 
spines from the second to the eleventh joint. The armature of these joints and of 
the anterior half of the twelfth consists of a rather prominent and posteriorly 
directed row on the anterior margin of each joint, followed by numerous smaller 
prickles, which decrease in size and abundance toward the posterior margin of the 
joint. The posterior half of the terminal joint is armed with very much larger and 
slightly curved prickles or spines, which point posteriorly on one side and anteriorly 
on the other(see fig. 43,h). Theanal spiracles are represented by dark cireular spots, 
and terminate in two prominent spines. The anterior spiracles appear as two minute 
elevations, and the mouth parts consist of two dark crescent-shaped hooks, the 
upper extremity of which projects, and two long supporting rods which fureate 
basally, and on the tips of which the hooks articulate (fig. 43, f, g). 
