46 



HIBERNATION OF THE COTTON BOLL WEEVIL. 



entrance into hibej-nation. The records indicate that there is a most 

 favorable time for entrance during which weevils may find shelter 

 from which they will emerge rather later than the average during the 

 following spring. 



THE RELATIONSHIP OF ACCUMULATED EFFECTIVE TEMPERATURE TO 



EMERGENCE. 



In studying the relationship of accumulated effective temperature 

 to emergence the initial point has been set arbitrarily at February 1. 

 It would be both interesting and profitable if we could determine 

 positively the exact effective temperature conditions under which 

 emergence from hibernation begins. This point will be further dis- 

 cussed in the light of the additional records obtained in Texas in 1907. 



The object in this particular study is to determine the relation 

 of accumulated effective temperature to the accumulation in emer- 

 gence. The records for both Keatchie and Dallas are included for the 

 sake of comparison. 



Table XXIII. — Relation of accumulated effective temperature to the beginning and 

 accumulation of emergence, Keatchie, La., and Dallas, Tex. 



Periods of emergence. 



1906 



Feb. 28 



Mar. 1-14 



Mar. 15-21 



Mar. 22-27 



Mar. 28-Apr. 2 



Apr. 3-13 



Apr. 14-20 



Apr. 21-May 5 



May 6-13 



May 14-23 



May 24-29 



May .30-Jnnell 



June 12-30 



Acciunulated ef- 

 fective tempera- 

 ture. 



Keatchie. 



"F. 



145. 



282. 



294. 



435. 



472. 



747. 



866. 

 1,350. 

 1,526. 

 1,865. 

 2,066. 

 2,479. 

 3,146. 



Dallas. 



°F. 



208.6 

 325.0 

 330.5 

 482.3 

 548.9 

 792.5 

 916. 6 

 ,362.4 

 ,512.2 

 ,812.4 

 ,009.2 

 ,487.6 

 , 188. 



Accumulated num- 

 ber of weevils 

 emerged. 



Keatchie. Dallas, 





 

 



25 

 37 

 202 

 230 

 417 

 466 

 639 

 662 

 727 

 734 



Accumulated per- 

 centage of total 

 emergence. 



Keatchie. Dallas 















3.4 



5.0 



27.5 



31.3 



56.8 



63.4 



87.0 



90.0 



99.0 



100.0 















3.6 



3.6 



54.5 



54.5 



87.2 



87.2 



100.0 



Emergence at Dallas became complete with the accumulation of 

 slightly over 1 ,800 degrees of effective temperature, while at Keatchie 

 complete emergence required slightly over 3,000 degrees of effect- 

 ive temperature. At Dallas 87 per cent of weevils had emerged 

 when 1,512 degrees of effective temperature had accumulated and 

 the same percentage had emerged at Keatchie with 1 ,865 degrees 

 effective temperature. For the last 13 per cent of weevils emerging 

 but 300 degrees of temperature accumulated at Dallas, while at 

 Keatchie nearly 1,300 degrees accumulated. It is probable that at 

 Dallas during this season the emergence in the cage was completed 

 somewhat sooner than would have been the case normally, on account 

 of the late period of starting the experiments. 



