PINK BOLLWORM OF COTTON IN MEXICO. 
Table XIX .— Mortality of larvae of P. gossypiella. 
39 
Num- 
ber of 
plants. 
On plant. 
Number of 
larvae. 
Pupae 
found. 
Exit 
holes. 
Larvae, 
pupae, 
and 
exit 
holes. 
Per 
cent 
mor- 
tality. 
Remarks . 
Num- 
ber of 
shells. 
Num- 
ber of 
eggs. 
In 
squares. 
In 
bolls. 
1 
1 
1 
1 
1 
181 
141 
190 
170 
103 
89 
111 
115 
53 
143 
3 
1 
6 

2 
17 
46 
84 
25 
39 



3 

7 
12 
24 
13 
15 
27 
59 
114 
41 
57 
85.1 
58.2 
40.0 
75.9 
44.7 
16 bolls on plant. 
28 bolls on plant. 
5 
785 
511 
12 
211 
3 
72 
298 
62.1 
From this table it is seen that the mortality varies from 40 to 85.1 
per cent with an average of 62.1 per cent. If it is assumed that 
none of the larvae from the 47.1 per cent of the eggs laid on other 
parts of the plants ever succeed in entering the bolls or squares, this 
would still leave 15 per cent of the larvae from eggs laid on the squares 
and bolls unaccounted for. Since many eggshells had undoubtedly 
fallen from the plants examined, this percentage of mortality (62.1 
per cent) is smaller than what actually occurs. 
To determine what percentage of the eggs laid on the bolls are 
lost, 16 samples of 25 green bolls each were examined, the number of 
eggs laid on them counted, and the total infestation found (Table 
XX). 
Table XX. — Mortality of pink bollworm larvae from eggs laid on bolls. 
Eggs. 
Larvae. 
Exit 
holes. 
Pupae. 
Total 
infes- 
tation. 
Per cent 
of larvae 
Number of bolls. 
Tip. 
Base. 
Total. 
First. 
Second . 
Third. 
Fourth. 
from 
eggs laid 
on bolls 
recovered 
in bolls. 
400 
61 
0.15 
4,958 
12.4 
5,019 
12.5 
190 
0.47 
347 
0.87 
442 
1.1 
1,005 
2.5 
386 
0.06 
1 
2,371 
5.92 
45.8 
There were 5,019 eggs and eggshells on the bolls. If larvae from 
all these eggs had hatched and all the larvae gone into the bolls, there 
would have been an average infestation of 12.5 larvae per boll, whereas 
an average of a little less than 6 larvae was actually found. These 
examinations were made in October and later examinations showed 
that the maximum infestation ever reached was an average of 7 per 
boll. 
These figures indicate that about half of the larvae from eggs laid 
on the bolls themselves never succeed in entering them. In Table 
III it was shown that 51.7 per cent of the eggs were laid on the bolls 
and appendages, and if only half of these successfully enter the bolls 
this would be equal to 25.8 per cent of the total eggs. This loss of 
