32 
BULLETIN 1374, U. S. DEPARTMENT OF AGRICULTURE 
A higher mortality among the larvae and pupae "between the rows 
than among those immediately under the rows is noted. 
Table 26 shows the relative mortality among pink bollworms at 
different depths in the soil. The mortality is greatest in the first 
2 inches of soil, decreasing with the depth. An average for all depths 
in this table gives 19.7 per cent mortality. 
Table 26.— Mortality of the pink boll 
worm t 
it different depths in 
the so' 
2 
First 2 inches 
Second 2 inches 
Third 2 inches 
Date of examination (1921) 
Larvae and 
pupae 
Pupal 
cases 
Larvae and 
pupae 
Pupal 
cases 
Larvae and 
pupae 
Pupal 
Living 
Dead 
Living 
Dead 
Living 
Dead 
July 21 
5 
70 
3 
31 
11 
2 
4 
8 
18 
17 
17 
3 

2 

13 
45 
2 
6 
39 
9 

16 
5 
12 

5 
3 
5 

2 
25 
3 
2 
2 
8 
1 

1 

2 
2 


19 
15 
Sept. 6 - ... .- 

25 
1 
Oct. 18 

1 


2 
3 

29 
j 

Total 
126 ! 65 
114 
34 
13 1 35 
13 i 5 
Ifi 
305 
82 • 
34 
Percentage dead 
21.3 
15.8 
14.7 
MORTALITY OF LARVAE IN THE RESTING STAGE 
The pink bollworm larva passes its resting period in or about seed 
or seed cotton in gins and warehouses, in the bolls in the field, and 
in the soil. As the activity of the insect lessens in the fall, an increas- 
ing percentage of the larvae spin up in the boll and assume the resting 
stage. This shows their normal preference for hibernating quarters. 
Larvae that hibernate in the soil evidently do so because the boll in 
which they mature does not offer suitable quarters. It may either 
still be green when the larva is ready to make its cocoon, or it may 
have fallen to the ground, where the sun's heat becomes so excessive 
that the larva enters the soil. 
MORTALITY OF LARVAE IN BOLLS AND SEED IN STORAGE 
One hundred bolls collected from standing stalks in the field on 
March 9, 1921, showed a total of 109 living larvae and 15 dead ones. 
Bolls ki storage furnish equally as good quarters for the resting 
larvae. Of the larvae in bolls that had been collected from the fields 
in the middle of November, 1921, and stored, 10 per cent were dead 
in March, 1922, and in others that were collected early in December, 
1922, 7 per cent were dead on February 7, 1923. Usually the larvae 
in seed or bolls in storage are attacked by mites, and mortality from 
this cause rises very rapidly in the spring. 
Tables 12 and 13" give records of larvae in stored seed and bolls of 
the 1920 and 1921 crops. According to these data, the larvae survive 
longer in bolls than in the seed. As all this material was stored 
under the same conditions in the laboratory, the most likely explana- 
tion for the difference is that larvae in loose seed are more accessible 
to mites than those in the bolls. The more rapid decrease of the 
