SUMMARY AND CONCLUSIONS, 97 



the infested area. This was the season of most exceptional rainfall 

 and cold, and it was not surprising that no weevils survived in the 

 cage tests except at Victoria, which was the southernmost point 

 of experiment. An average for the six localities shows a survival of 

 less than two-thirds of 1 per cent. In the small-cage work of 1905-6 

 there was an average survival of 1.3 per cent, and practically all of 

 this occurred in the outdoor cages. 



The most important work done in 1905-6 was in a large cage at 

 Keatcliie, La., where 25,800 weevils were placed in 18 compartments. 

 The survival in this cage was 2.82 per cent, and the emergence oc- 

 curred between March 22 and June 28, 1906. The cages having 

 nearest to the ordinary field conditions with poor cultivation gave 

 the largest percentage of successful hibernation. A study of the 

 emergence and temperature records for similar experiments at Dallas, 

 Tex., and Keatchie, La., shows that at the former place approximately 

 50 per cent of the emergence occurred while the temperature ranged 

 between 58 and 68 degrees, while at the latter place one-half of the 

 total emergence took place while the temperature ranged between 

 about 65 and 75 degrees. Very few weevils emerged while the tem- 

 perature was below 57 degrees. 



There is an optimum period for entrance into hibernation, and 

 weevils entering during this period have a considerably better chance 

 of surviving than do those which enter either earlier or later. If 

 hibernation is begun earlier than this optimum period, it is likely that 

 emergence will be completed earlier during the following season, and 

 also if entrance occurs later than this period it is likely that emer- 

 gence will begin unusually early in the following sprmg. 



Variation in the period of entrance into hibernation and the dif- 

 ference in the nature of the shelter secured by the weevils may rea- 

 sonably account for the variations found in the amount of accumu- 

 lated effective temperature required to produce complete emergence 

 in the spring. 



Weevils emerging earlier in the season survived for a longer period 

 than did those which emerged after the middle of the emergence 

 period. It is a common occurrence for weevils to leave their winter 

 quarters upon warm days in spring, returning again to a condition 

 of inactivity for a period of several days or even weeks. Disappear- 

 ance and reappearance in the case of plainly marked individuals has 

 been observed to occur as many as eight times, and a maximum 

 period of forty-three days between appearances has been recorded. 

 These facts argue very strongly indeed against the proposition which 

 is sometimes made by those who are not thoroughly familiar with the 

 habits of the weevil, to starve the emerged weevils by deferring the 

 planting of cotton in the spring. Two lots of 20 and 8 weevils sur- 

 90317— Bull. 77—09 7 



