34 BULLETIN 1374, U. S. DEPARTMENT OF AGKICTJLTUEE 
Table 27. — Mortality of resting -pink bollworms in the soil in the fields, 1921 and 
1922 
Month 
Percentage of 
mortality 
1921-22 1922-23 
10 38.9 
26.6 ! 22.8 
January. . 
24.2 1 26.4 
February.. . .___. ... 
34. 9 26. 1 
March .. . . _-_____--___._ __-__i__ _. . ... ... .. 
41.4 
29.5 
39.8 
60.0 
100 
33. 1 
April 
May.. . . . . .... . . 
July 
These records are based entirely on actual field examinations, 
which explains their irregularity. In the first place there is an 
accumulation of dead larvae and pupae from the summer and fall. 
And as the larvae assume the resting stage in the soil gradually, 
it is not possible to consider a certain percentage of the dead an 
accumulation of the summer stages and subtract this from all sub- 
sequent records. Again, a gradual decay of dead larvae, which are 
consequently not found in the examinations, will make the figures 
for dead too low in the later examinations. Lastly, emergences of 
moths have not been considered at all in these figures, because pupa] 
cases are to a great extent destroyed in preparing the soil for exami- 
nation. The records for 1922-23 are based on examinations of more 
soil than those for 1921-22. Also the soil all came from the same 
field, which was not the case in 1921-22. Individual figures for the 
second season are therefore more comparable than for the first. 
The decrease in the percentage of dead for December, 1922, was 
due to the cutting of the cotton stalks at the end of November, 
which, as has been pointed out, caused the shedding of many bolls 
and a consequent issuance of many larvae from these bolls and 
entrance into the soil. From data in Table 7, an increase is cal- 
culated in the average number of living larvae and pupae per square 
yard of soil from 6.4 for November to 18.6 for December. 
The records in Table 27 give no indication of the total mortality 
during the resting period and the percentage of the larvae that 
finally transform to the moth stage. In connection with an experi- 
ment on the effect of winter cultivation, some cages were placed in 
the field to catch moths emerging from the soil in the spring. This 
experiment is described in detail in this report, under " Winter 
plowing.'' A partly calculated record of an emergence of 2.2 moths 
per square yard from an uncultivated part of the field which aver- 
aged 14 living larvae per square yard during March and April is 
given. This would show a mortality of about 84 per cent of the 
larvae that pass the resting period in the soil. 
PARASITES 
In the spring of 1921 an experiment was started to determine 
whether daily picking of all infested blooms would reduce the pink 
bollworm infestation. A half-acre plat was selected for this test, 
and work was commenced June 17. After a few davs a considerable 
