26 
BULLETIN 746, U. S. DEPARTMENT OF AGRICULTURE. 
Table V. — Relationship of mean temperature to developmental period in larva 
stage of the sugar-cane moth borer — Continued. 
Mean tem- 
Average 
Number 
Mean tem- 
Average 
period. 
Number 
perature. 
period . 
of records. 
perature. 
of records. 
°F. 
Days. 
°F. 
Bays. 
70 
45 
1 
81 
45 
2 
70.6 
39 
1 
81.5 
35.1 
7 
70.8 
34 
1 
81.7 
46 
1 
71.4 
33 
1 
82 
50 
2 
71.7 
35 
1 
82.1 
65 
1 
71.9 
37 
1 
82.2 
54.5 
2 
72 
38 
2 
82.4 
52 
1 
72.1 
38.5 
2 
82.5 
57.6 
3 
72.2 
22 
1 
82.6 
42.5 

72.3 
37 
2 
82.7 
40.4 
5 
72.9 
24 
1 
82.8 
36 
12 
73.3 
25.8 
5 
82.9 
31.1 
19 
73.5 
27 
1 
83 
24.3 
6 
73.9 
28 
1 
83.1 
31 
1 
74 
39 
1 
83.3 
71 
1 
74.4 
49 
2 
83.4 
34 
1 
75.1 
54 
2 
83.7 
34 
2 
75.4 
33 
1 
83.8 
32.8 
7 
76.1 
60.3 
2 
83.9 
38.8 
10 
76.2 
66 
2 
84 
24 
3 
76.3 
26 
1 
84.1 
45.5 
4 
76.5 
27 
1 
84.2 
29.7 
8 
76.8 
28 
1 
84.3 
38.5 
2 
77.1 
32 
2 
84.4 
29.6 
9 
77.2 
38 
2 
84.5 
20.5 
9 
77.5 
31 
1 
84.6 
25.5 
5 
78 
34 
1 
84.8 
25.5 
2 
78.1 
71 
1 
84.9 
26.2 
13 
78.2 
28 
3 
85 
25 
8 
78.3 
48 
1 
85.1 
19 
1 
78.5 
22 
1 
85.4 
54 
1 
PUPAL CELLS. 
When the larvse are fully grown they construct a kind of pupal 
cell before pupating. The larval tunnel is cleaned, enlarged, and 
extended to the rind of the cane, where a small circular opening 4 to 
5 mm. in diameter is made. The rind is not completely cut out, 
but it is eaten away from the inside until only a thin paperlike 
section, lightly attached at the edges, remains. This is held in place 
by threads of silk fastened to the inside so that the moth can easily 
escape, but other insects can not enter. The lower end of the cell 
is closed with frass and silk, and the whole cell is lightly lined with 
silk. In the rearing tubes in the insectary the pupal cell usually is 
formed on the side of the cane between it and the sides of the glass. 
PREPUPA. 
As the pupal cell nears completion the larva merges into the pre- 
pupa stage. No molt occurs, but the larva ceases feeding and 
becomes sluggish and helpless. The body contracts longitudinally, 
especially the thorax, while the use of the legs is lost and the insect 
thrashes about as do the pupae. From 1 to 3 days are spent in the 
prepupa stage, but it often happens that this stage is not noticed by 
an observer, as it is not very distinct from the larva stage. 
PUPATION. 
After resting for a short time as a prepupa the pupa is disclosed 
by the casting of the last larval skin in the same manner as the 
others are cast. 
