1168 
Journal of Agricultural Research 
Vol. XXVIII, No. 12 
older larvae in that the anterior end is the larger, the body tapering toward a 
pointed posterior end. In old larvae the posterior end is blunt and rounded. 
In larvae of all ages the body is strongly flexed toward the ventral side. In 
marked contrast the larvae of the Vespidae have bodies which are nearly straight. 
In color the larva is ivory white. As seen in the comb it appears to be pure 
white by contrast with the brown comb, but when removed and placed on a 
white surface it takes on a yellowish or brownish tinge. 
A series of sharply defined constrictions divides the body into 13 segments, 
3 thoracic and 10 abdominal. 3 In antero-posterior extent the three thoracic 
segments are subequal and slightly inferior to the adjacent abdominal segments. 
The latter are also subequal in extent, with the exception of the 9th and 10th. 
The 9th is short and has a somewhat discoid form, as shown in the figure. The 
10th is quite small and also discoid and bears in its center a low papilla on which 
is situated the anal opening. 
The ventral or sternal surface is marked off from the lateral surfaces by a 
deep groove, the ventrolateral suture (PI. 1, D, VIS), which extends from the 
1st to the 8th abdominal segments, being absent on the three thoracic and the 
last two abdominal segments. The lateral surfaces of the abdominal segments, 
with the exception of the last two, are raised to form rounded lobes, the epi- 
pleural lobes ( EpL ). These lobes, while sharply marked off from the ventral 
surface by the ventrolateral suture, merge almost imperceptibly into the dorso¬ 
lateral surfaces of the body. The epipleural lobes are often more or less con¬ 
fluent, producing the appearance of a beaded ridge on each side of the body. 
The abrupt termination of these ridges at the posterior boundary of the third 
thoracic segment produces the appearance of “shoulders” noted by White ( 50 ). 
Ten pairs of spiracles are present, belonging as usual to the 2d and 3d thoracic 
and the first eight abdominal segments. They appear externally as minute 
circular apertures, each of which is surrounded by a narrow chitinous ring, the 
peritreme. They are located at the same level on all of the segments, about 
half way between the dorsal mid-line and the ventrolateral suture, and lie close 
to the anterior edges of their respective segments in depressions confluent with 
the intersegmental constrictions. In the thoracic region the first pair of spir¬ 
acles has the appearance of belonging to the 1st instead of to the 2d thoracic 
segment, this appearance being due to the somewhat peculiar outline of the 
contiguous margins of these two segments (see fig. 4, A). Below the spiracles 
of the 2d and 3d thoracic segments the oval outlines of the wing rudiments 
(WngR) may be somewhat indistinctly seen. On all of the segments bearing 
spiracles a shallow linear depression or suture arises in the neighborhood of 
each spiracle and takes an oblique course dorsad and caudad across the dorso¬ 
lateral surface of the segment toward the dorsal mid-line, where it disappears, 
thus separating the dorsal half of the segment into anterior ( Prs ) and posterior 
(Scs) divisions. Comparison with coleopterous larvae, such as those of Den- 
droctonus (17), makes it evident that the anterior division corresponds to the 
prescutum, while the posterior, which is confluent laterally with the remainder 
of the segment, corresponds to the scutum and scutellum together, which in 
the coleopterous larva are separated by a suture. These divisions, and in fact 
the entire contour of the body, are intimately related to the internal structure, 
as will be more completely explained in the description of the muscular system. 
The head (PI. 1, F, G), with regard to its general outline, may be described 
as bluntly conical, the base of the cone being formed by the head capsule, the 
apex by the labrum and the other mouth parts. The head is joined to the 
3 Embryological evidence indicates that there are actually 12 segments represented in the abdomen of 
the bee larva ( 86 , 88 ). 
