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BULLETIN 1374, TJ. S. DEPABTMENT OF AGEICULTURE 



It will be noted that the records for 1921 fields show no livmg 

 pupse 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 pupse 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. 



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Fig. 5. — Bolls placed on surface of soil to determine extent to which larvae will leave these bolls and 



enter soil for hibernation 



NUMBERS OP STAGES IN SOIL AND IN BOLLS ON SURFACE OP 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 boUworm. 

 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. 



