46 
BULLETIN 918, U. S. DEPARTMENT OF AGRICULTURE. 
in the seed warehouses, because the dead larvae are so hard to find, 
but it is evident to one collecting larvae that it is much higher in 
the early spring than in the fall. The mortality was 80 per cent 
among larvae thrown out by the cleaners and stored indoors during 
the winter, and in this sample only the most active larvae were used. 
Table XXIII. — Mortality among laryx in double seeds removed from lint by hand and 
stored in jars in the laboratory. 
Date collected. 
Number 
entering 
resting 
stage. 
Number 
emerged. 
Per cent 
mortality. 
Per cent 
emerged. 
Number 
alive Nov. 
20, 1919. 
1918. 
Nov. 15 
206 
190 
184 
88 
61 
213 
172 
182 
165 
157 
76 
41 
119 
143 
8.7 
9.4 
8.1 
9.0 
22.9 
41.3 
11.6 
88.3 
86.8 
85.3 
86.3 
67.2 
55.8 
83.1 
6 
7 
12 
4 
6 
6 
9 
Nov. 22 
Nov. 23 
Nov. 22 
Do 
Dec. 25 
1919. 
Jan. 23 
Total 
1,114 
883 
50 
4.4 per cent. 
16.2 
79.2 
MORTALITY OF LARV^ PLANTED WITH THE SEED. 
A screen-wire cage was built so that no infestation could interfere 
from the outside, and 100 double seeds were planted with sound 
seed in 30 hills to see what the infestation would be from larvae 
planted with the seed alone. No infestation occurred during August, 
but from September 1 to November 7 the infestation went from 
12 per cent to 96 per cent, with an average of 5.6 larvae per boll on 
November 7. Thus it is evident that should all the larvae left in 
the fields be destroyed either naturally or by artificial means, the 
infestation arising from the larvae planted with the seed alone is 
sufficient to cause a considerable loss (Table XXIV) . 
Table XXIV. — Infestation of pink bollworm from 100 double seeds planted in a cage. 
Date examined. 
Per cent 
of bolls 
infested. 
Average infestation per boll. 
Larvse. 
Pupa?. 
Exit holes. 
Total. 
1919. 
Aug. 1 



12.00 
84.00 
96.00 



0.12 
2.20 
5.60 










0.96 




0.12 
3.16 
5.60 
Aug. 6 
Aug. 22 
Sept. 1 
Sent. 30 
Nov. 7 
PARASITES AND PREDATORS. 
What part of the mortality in the newly hatched larvae is due to 
starvation, exposure to the sun, or falling from the plants, and 
what to predacious insects, could not be determined, but the toll 
