10 BULLETIN 1374, U. S. DEPARTMENT OF AGRICULTURE 
It will be noted that the records for 1921 fields show no living 
pupae at any time during the period from September 25, 1921, to 
June 12, .1922, inclusive. This would indicate that any larvae that 
enter the soil after about the middle of September prepare to hiber- 
nate. No doubt some pupae were killed by the sifting and washing; 
but, if any number of living pupae had been present, some certainly 
would have been found, considering that during this period 44 square 
yards of soil were examined and 358 living larvae found. Some of 
the larvae that hibernated in the soil must have pupated long before 
the time of the first record of living pupae, June 26, 1922. The 
records for 1922 show living pupae in samples of soil as late as October 
23, and again on December 13. In fact, there are indications that 
pupation occurred throughout the winter, and living pupae were 
found on February 7 and 21. In another experiment a living pupa 
was found in a cocoon in the soil on January 22, 1923. The con- 
sistent finding of a rather large number of pupal cases throughout 
December, January, and February, shown in Table 7, also points to 
some pupation throughout this period. 
!_. _ __ •_ _ „__ ______ 
Fig. 5.— Bolls placed on surface of soil to determine extent to which larvae will leave these bolls and 
enter soil for hibernation 
NUMBERS OF STAGES IN SOIL AND IN BOLLS ON SURFACE OF SOIL AND ON STALKS 
DURING WINTER COMPARED 
An experiment was begun at the end of November, 1922, to deter- 
mine the relative importance of soil, bolls on the surface of the soil, 
and bolls on stalks as hibernating quarters for the pink bollworm. 
Although this experiment has not been completed and so does not 
show the results at the end of the hibernating period, it indicates the 
extent to which the pink bollworm enters the soil for hibernation 
under the different conditions. Bolls were collected from standing 
stalks in the field at the end of November. These were divided into 
lots of 100 bolls each. One lot examined on November 28 showed 
the extent to which the bolls were infested then. On the following 
day 15 lots were placed on the surface of the soil in the garden (fig. 5), 
where there had been no cotton and consequently no larvae in the soil. 
