THE SUGAR-CANE MOTH BORER. 
27 
PUPA. 
The pupa at first is dirty white, about the same color as the 
hibernating larva, with faint purplish longitudinal stripes. It 
gradually hardens and darkens, and in an hour or two becomes 
mahogany brown. As the time for emergence approaches the pupa 
darkens more and may become almost black. 
ACTIVITY. 
The pupa is quite active when disturbed, being able to thrash 
about with its abdomen, which gives it a rolling, squirming motion. 
A touch or a jar will cause this action, as will also the placing of the 
pupa in direct sunlight in summer. Placed in the sun, a pupa 
squirmed about till it reached a shady place. 
DURATION OF PUPAL PEEIOD. 
The first pupae in the spring are formed from overwintering 
larvae in April or May, and pupae may be found from this date to 
December. Few larvae pupate after the middle of November, those 
which have not pupated prior to this time hibernating as larvae. 
Nearly 200 larvae were collected in cane cut for the mill on December 
2-4, 1915, but no pupae were found in all the stalks cut open. Adults 
have emerged from pupae in the insectary as late as December 5, but 
a large percentage of those which did not pupate until late and had 
the pupal period prolonged by cold did not emerge. 
The pupal period, like that of the larva, has a w,ide variation, from 
6 to 22 days being required for the emergence of the adult, with an 
average of 8J days throughout the year. The pupae which produced 
male moths required on an average 8.8 days for emergence, and those 
which produced females 8.4 days. Often there is a variation of 2 to 
3 days among pupae which transform on the same date. The data 
are presented in Table VI and figure 9. 
Table VI. — Relationship of mean temperature to the developmental period in 
the pupal stage of the sugar-cane moth borer. 
Period. 
Average 
mean tem- 
perature. 
Number 
of records. 
Period. 
Average 
mean tem- 
perature. 
Number 
of records. 
Days. 
5 
6 
7 
8 
9 
10 
11 
12 
° F. 
77.1 
82.3 
81.1 
81.3 
80.9 
76.6 
76.1 
74 
3 
27 
153 
92 
42 
19 
12 
4 
Days. 
13 
14 
15 
16 
17 
18 
19 
22 
° F. 
71.6 
79.7 
73.9 
77 
72 
69.8 
84.6 
63.7 
1 
7 
5 
5 
1 
1 
3 
1 
DURATION OF THE LIFE CYCLE. 
The length of the life cycle varies considerably with the tempera- 
ture. Taking the minimum of each immature stage, the sum of 28 
days is obtained, while in the same way a maximum of 293 days is 
