82 



longitudinal groove in the stalk and within the slielter of the clasping 

 base of the leaf. Perhaps the most favorable of all hibernating con- 

 ditions are to be found among the leaves and rubbish abounding in 

 the edges of timber adjoining cotton fields. From such places the 

 weevils are known to come in large numbers in the spring. The 

 timber fringes present greater difficulties in the way of removing the 

 favorable conditions than do any of the other places mentioned. 



Temperature and available food supply seem to be the most impor- 

 tant factors in determining the time of hibernation. In general, it 

 may be said that many weevils are active so long as their food con- 

 tinues in fit condition to sustain them. Some, liowever, undoubtedly 

 seek shelter before frosts occur. From numerous observations made 

 in the laboratory, it appears that weevils will starve when deprived of 

 cotton if the mean average temperature continues long above a point 

 somewhere between 60° and 65° F. As the mean average falls below 

 60° hibernation may take i^lace suceessfull}'. 



It is a very significant fact that of the 240 weevils taken from the 

 field at the middle of December, 1902, and placed in hibernation, 38, 

 or 15 8 per cent, passed the winter successfully, while of the 116 

 weevils adult before November 15, 1903, only 1, or less than 1 j)er 

 cent, survived. It is evident that the weevils which pass the winter 

 and attack the crop of the following season are among those developed 

 latest in the fall and which, in consequence of that fact, have not 

 exhausted their vitalit}^ by oviposition or any considerable length of 

 active life. 



LENGTH OF HIBERNATION PERIOD. 



As the observations upon this point have all been made at Victoria, 

 Tex., the statements made refer especially to that locality. It must 

 be borne in mind that latitude and altitude, as well as seasonal varia- 

 tions, will influence the limits of this period. In general, however, it 

 may be said that hibernation begins at about the time of the first 

 hard frost, and that it continues until the mean average temperature 

 has been for some time above 60° F. In the spring of 1903 weevils 

 left hibernation quarters at Victoria only Avhen the mean average 

 temperature had been for some time at about 68° F. While it is true 

 that weevils if disturbed in hibernation are active at much lower 

 temperatures than this, for some reason they do not leave the shelter 

 of their hibernation places. 



At Victoria, Tex., the average hibernation season may be said to 

 extend from about December 1 to about April 1, or a j)eriod of about 

 4 months. In more northern latitudes hibernation will, as a rule, 

 begin earlier and last later, covering a period of from 4 to 5 months. 



