98 HIBERNATION OF THE COTTON BOLL WEEVIL. 



vived for an average of thirty and sixty days, respectively, after emer- 

 gence without a particle of green food from the time of their entrance 

 into hibernation to the time of their death. Other tests show similar 

 results. 



The hibernation experiments of 1906-7 consisted of large-cage 

 work in three localities representing the northern, central, and 

 southern portions of tlie infested area. Each cage inclosed 10 sepa- 

 rate experiments and the comparisons made possible by the three 

 locations, the different shelter conditions, and the different dates of 

 instituting the experiments furnish the basis for the most complete 

 and significant work which has been done with the hibernation of the 

 weevil. 



Owing to the exceptional mildness of this season, complete hiber- 

 nation did not occur at any time during the winter in any part of 

 Texas. Emergence began during the last week or ten days of Feb- 

 ruary, 1907. At Dallas 7.8, at Calvert 10.5, and at Victoria 27.7 per 

 cent of the total numbers of weevils placed in the cages were counted 

 as being active at some time during the winter season when they 

 should normally have all been in complete hibernation. About 13 

 per cent of the adult weevils buried with a lot of bolls under 2 inches 

 of heavy, black soil escaped and were found upon the cage screen dur- 

 ing the next few days. Weevils were active in the field as well as in 

 the cages during this winter. The period of greatest emergence oc- 

 curred during the latter part of March, which was undoubtedly from 

 four to six weeks earlier than is usual. Succeeding low temperatures 

 served to prolong the period of emergence until the 1st of July. In 

 the three localities under observation an average of 11.5 per cent of 

 the 75,000 weevils placed in the experiments survived and emerged 

 in the spring of 1907. 



Grouping the experiments in the three localities according to the 

 dates of installation of the weevils and averaging the percentages of 

 survival in each group, it appears that there was a steady increase in 

 this percentage upon succeeding dates after the middle of October, 

 when the experiments were started, to the end of November, when 

 the last weevils were placed in the cages. This increase is so nearly 

 regular as to prove conclusively that the date at which weevils are 

 deprived of food in the fall, in its relation to the most favorable period 

 for entrance into hibernation, has a most vital influence upon the 

 prospect for survival. Among the weevils started October 14 but 

 3.14 per cent survived, while among those started just one month 

 later an average of 19.67 per cent survived. These results prove 

 absolutely the advisability of destroying the food supply of the 

 weevils at least three weeks before the usual time for the first frosts 

 to occur, and they show very plainly just why such a practice is the 



