1912] Life History of a New Psychoda 415: 
At the time of hatching the larva is small, measuring only 
about 0.5 mm. It is whitish in appearance and quite trans- 
parent. It is active from the time of the emergence from the 
egg, and increase in size takes place rapidly. At this stage the 
two reddish-brown eye spots on the lateral aspect of the head 
are quite distinct. Immediately after hatching the little larva 
places itself, if possible, in a position which allows the breathing 
tube to be exposed to the air. 
The mature larva is cylindrical, slender, and from 8.5 mm. to 9.5 
mm. long. The greatest diameter, which occurs in the anterior region 
of the body, is about 1 mm. The color is light brown. In the mid 
abdominal region a whitish or silvery appearance is common and is 
in part due to the fact that the longitudinal tracheal trunks show 
through the integument to some extent. The body is composed of the 
head, three thoracic segments, and eight abdominal segments. 
The head is much smaller than the adjacent thoracic segment. It is 
smooth, deep brown in color, and strongly chitinized. A pair of oval 
brown eye spots are present on the anterior lateral aspect. The head is 
to some extent retractile, and may be partially withdrawn into the 
thorax. The lateral margins of the clypeus converge posteriorly. 
Minute antennz appear as a number of tiny rods of similar shape and 
size. The tip of the labrum is spiny and also bears a few sete. The 
mouth parts, which are setose and denticulate, are enclosed in a sunken 
space on the anterior part of the ventral aspect of the head. On either 
side of the labrum and attached to the ventral surface is a pair of setose 
segmented appendages which in the living larva are in constant motion 
being rapidly extended and retracted and apparently serving as pre- 
hensile organs. Two pairs of clusters of setae occur laterally, one pair 
near the eye spots and the other pair nearer the prothoracic segment. 
Setze also occur on the dorsal aspect of the head, one aggregation located 
midway between the eye spots, two setz near the middle, and two sete 
near the caudal margin. 
The thoracic segments are distinct and each shows one well marked 
constriction which divides it into an anterior and a posterior annulus. 
The posterior annulus of the prothoracic segment bears four groups of 
setae (usually two in each group), two dorsal and two ventral. The 
ventral group usually has one long seta. The dorsal surface of the pos- 
terior prothoracic annulus bears two small brown protuberances, one 
on either side and dorso-lateral in position. The tip of each protuberance 
bears a closed spiracle which is the terminus of a branch of the tracheal 
system. The mesothorax and metathorax have one constriction each, 
and in other respects are similar to the prothorax, with the exception 
that the diameter is slightly increased. The thorax as a whole is smooth, 
and the fine chitinous surface spines are much smaller than those on 
the abdominal segments. 
The first abdominal segment has one constriction, but the following 
six have two thus marking off each segment into an anterior, a median, 
and a posterior annulus. The sete on the first segment are arranged as 
in the thoracic segments, while in the following segments ventral groups. 
