48 JOURNAL OF ENTOMOLOGY AND ZOOLOGY 
In the dorsal part there are five, sometimes six, large air sacs 
on each side. These arise at the spiracles and, with the excep- 
tion of the first, are paired. The first, as shown in Fig. 1, A, 
is connected with a smaller air sac. In front of each pair of 
large sacs is also a pair of smaller ones, about the same width 
but only one-half as long as the larger and at the lower end 
connected with the large ones by a small tube. Each large air 
sae is also connected with the lower part of the small one 
posterior to it. 
Figure 2. Ventral view of the ventral tracheal air sacs of abdomen. X3. 
A—Main air sacs of ventral system. 
B—Lateral longitudinal trachea. 
C—Variation in number and arrangement of ventral air sacs. 
There are some variations in the arrangement of these en- 
larged tracheal tubes. One is shown on the right side of Fig. 
1, A, where the large air sac is in front and two smaller ones 
lie side by side. In another instance two small air saes are 
connected to the first long one on the left side and there are 
no small ones connected with the second long one. At the 
caudal end there are several small sacs connected with each 
other and with one spiracle, as shown in Fig. 1, A. There are 
variations in this also, since in some a large air sac is connected 
