BIOLOGY OF THE MEXICAN COTTON BOLL WEEVIL. 



41 



last emergence was made by a weevil placed in the hibernation cage 

 on December 1. The dates on which 25, 50, and 75 per cent of the 

 weevils had emerged follow very closely the sequence of installation. 



Table XVIII. 



-Hibernation of the boll weevil in open field cages, winter 

 1918-19. 



Cage 

 No. 



Date 

 started. 



Num- 

 ber of 

 weevils 



in- 

 stalled. 



Date of 

 first 

 emer- 

 gence. 



Date of 

 last 

 emer- 

 gence. 



Date on 



which 



25 per 



cent had 



emerged. 



Date on 



which 



50 per 



cent had 



emerged. 



Date on 



which 



75 per 



cent had 



emerged. 



Period 

 of 



Number emerg- 

 ing. 



Per- 

 cent- 

 age of 



gence 



Males 



Fe- 

 males 



Total. 



sur- 

 vival. 



1 



4 



7 



10 



13 



1918. 

 Oct. 1 

 Oct. 15 

 Nov. 1 

 Nov.15 

 Dec. 1 



1,000 

 1,000 

 1,000 

 1,000 

 300 . 



1919. 



Feb. 20 

 ...do... 

 ...do.... 

 ...do.... 



Mar. 10 



Feb. 20 



1919. 

 Mar. 16 

 May 27 

 June 2 

 June 1 

 June 5 



1919. 

 Feb. 20 

 Mar. 1 

 Mar. 7 

 Mar. 16 

 Apr. 11 



1919. 

 Feb. 20 

 Mar. 8 

 Apr. 2 

 Apr. 17 

 May 4 



1919. 

 Mar. 16 

 Apr. 2 

 May 6 

 ...do ... 

 May 10 



Days. 

 24 

 96 

 102 

 101 

 87 



1 

 17 

 23 

 68 

 14 



1 



21 

 22 

 59 

 9 



2 

 38 

 45 

 127 

 23 



0.2 

 3.8 

 4.5 

 12.7 

 7.6 



Total 



4,300 



860 



1,000 



410 

 82 



102 

 24 



123 

 24.6 

 68 

 1 



112 



22.4 

 59 

 1 



235 



47 



127 



2 





Av 











5.76 

















12.7 







300 













.2 



















NUMBER OF BOLL WEEVILS SURVIVING THE WINTER WHEN HIBERNATING ON 

 THE GROUND IN THE WOODS. 



Woods shelter has always been considered one of the ideal places 

 for successful hibernation of the boll weevil. The results secured at 

 Madison showed a total percentage of survival of 12.8 as compared 

 to 5. 76 per cent for the open field. The results of the woods hiber- 

 nating experiments are presented in Table XIX. In every case the 

 emergence started from the cages on February 20. The cage in- 

 stalled October 1 gave the smallest percentage of emergence (0.8), 

 while the cage installed November 15 gave the highest emergence 

 (20.7 per cent). 



Table XIX. 



-Hibernation records of adult boll weevils in cages on ground in 

 woods. 



Cage 

 No. 



Date 

 started. 



Num- 

 ber of 

 wevils 



in- 

 stalled. 



Date of 

 first 

 emer- 

 gence. 



Date of 

 last 

 emer- 

 gence. 



Date on 



which 



25 per 



cent had 



emerged. 



Date on 



which 



50 per 



cent had 



emerged. 



Date on 



which 



75 per 



cent had 



emerged. 



Period 

 of 



emer- 

 gence 



Number emerg- 

 ing. 



Per- 

 cent- 

 age of 



Males 



Fe- 

 males 



Total. 



sur- 

 vival. 



2 



5.: 



8 



11 



14 



1918. 

 Oct. 1 

 Oct. 15 

 Nov. 1 

 Nov.15 

 Dec. 1 



1,000 

 1,000 

 1,000 

 1,000 

 300 



1919. 

 Feb. 20 

 do., 

 do., 

 do., 

 do.. 



1919. 

 Apr. 2 

 June 17 

 June 1 

 June 8 

 June 16 



1919. 



Feb. 20 

 Mar. 4 

 Apr. 4 

 Mar. 5 

 Mar. 12 



1919. 

 Feb. 26 

 Mar. 16 

 May 6 

 Apr. 2 

 May 7 



1919. 

 Mar. 4 

 Apr. 5 

 May 7 

 Apr. 28 

 May 7 



Days. 

 41 

 117 

 101 

 108 

 116 



4 



19 



115 



113 



30 



4 

 22 

 81 

 94 



27 



8 



41 



196 



207 



57 



0.8 

 4.1 

 19.6 

 20.7 

 19.0 



Total . 



4,300 

 860 



1,000 

 300 



483 

 96.6 

 117 

 41 



281 

 56.2 

 115 

 4 



228 

 45.6 

 94 



4 



509 

 101.8 

 207 



8 





Av 















12.8 

















20.7 

















0.8 



















