1947] 
Dilaridce and Berothidce 
149 
Thoracic segments without noticeable sclerotized 
plates; mesotlioracic spiracle in fold created by small 
anterior subsegment. Front legs somewhat more elon- 
gate and robust than middle and bind legs. Leg (fig. 21) 
with femur and tibia moderately compressed; tarsus dis- 
tinct but capable of little or no movement on tibia; tro- 
chanter weakly defined; front claws blunt with anterior 
claw decidedly shorter than posterior one (fig. 17) ; claws 
of middle and bind pairs much smaller than front ones, 
unequal but not conspicuously so; paired pulvilli (or 
similar pads) at base of claws; empodium slender, 
trumpet-shaped, segmented in apical third, a second line 
of segmentation indistinct. Abdomen uniformly, weakly 
sclerotized ; segments I-VIII with lateral spiracle in 
anterior third; each lateral margin of segments I-IX (on 
slide-mounted specimen) with two principal lobes, each 
lobe with a principal seta. 
Coloration: Head gamboge yellow, somewhat darker 
above ; thorax and abdomen uniformly pale, almost color- 
less; front claws light brown, middle and bind claws 
paler. 
The supposedly mature larvae of americanus range in 
length from 4.6 mm. to 12 mm., while the number of ring 
segments of the labial palpus and antenna vary as indi- 
cated above, and in several cases there is a difference of 
one segment in right and left appendages of the same 
specimen. The larva from College Park is the longest 
and has the largest number of antennal and palpal seg- 
ments, but the one from Jackson’s Island is the shortest 
(4.6 mm.) and has one more segment in each appendage 
than two larvae from University Park examined in detail 
(4.8 mm. long, 5 segments in each appendage). The sex 
of these larvae is naturally unknown, aside from the cast 
skin from which a male pupa developed. Adult males 
average definitely smaller than females. From the evi- 
dence now at band, it is accordingly uncertain whether 
all or only part of these larvae are fully developed, 
whether the number of palpal and antennal segments is 
variable from instar to instar, as well as in larvae of the 
same instar, and whether sex has a bearing on size of 
