28 



BULLETIN 358, U. S. DEPARTMENT OF AGRICULTURE. 



Table XXIII. — Total developmental period of the boll weevil: Observations of 1915. 



GRANDIS WEEVILS. 





Larval food. 



Oviposition 

 period. 



Males. 



Females. 



4) 



a . 



o 



Eh 



> 



<B 

 <C . 



£>> 

 03 



O 



E-i 



ft 



Source of weevils. 



s8 



si 





<B . 



s ° 



> 2 

 < ft 





Is 



® . 



® 



5 



Hibernated weevils 



Do 



First generation 



Cotton squares 



do 



do 



Junel-Aug. 23.. 

 June2-Aug. 23.. 

 June26-Sept. 7.. 

 July 23-Sept. 5.. 

 July 12-Sept. 16. 



971,383 

 911,264 



44 629 



Dys. 

 14.3 

 13.9 

 14.3 

 15.5 

 16.4 



105 



87 



54 



9 



13 



1,443 



1,193 



739 



131 



209 



Dys. 

 13.7 

 13.7 

 13.7 

 14.6 

 16.1 



202 



178 



98 



15 



20 



2,826 



2,457 



1,368 



224 



324 



14 



13.8 



14 



Second generation 



Grandis bred weevils . . 



do 



Cotton bolls. . . 



6 93 



7 115 



14.9 

 16.2 



Total 



245 2 4.84 



14.2 



268 



3,715 



13.9 



513 



7,199 



14 















THURBERIAE WEEVILS. 



Weevilsextracted from 

 bolls. 



First generation 



Extracted from bolls. . . 



Total. 



Cotton squares 



do 



Cotton bolls. 



June28-Sept.9.. 



July24-Sept. 20. 

 July28-Sept.24. 



55 



792 



14.4 



49 



70914.47 



104 



1,501 



16 

 4 



234 

 57 



14.6 

 14.3 



7 

 6 



95 13. 6 

 97 16. 3 



23 

 10 



329 

 154 



75 



1,083 



14.4 



62 



901 14. 5 



137 



1,984 



14.43 



14.3 

 15.4 



14.48 



Male grandis by female 



thurberiae. 

 Male thurberiae by fe- 

 male grandis. 



Total of all va- 

 rieties. 



Cotton squares 

 do 



June2S-Sept.7.. 

 June28-Sept. 19. 

 1915 



726 

 5,982 



13.78 

 14.0 

 14.2 



S27 



719 



6,162 



13.13 



14.1 



13.9 



1,516 

 1,445 



12, 124 



13.42 



14 



14 



The average total period for both sexes in both squares and bolls 

 was 14 days. The developmental period in bolls is seen to be greater 

 than in squares with both grandis and thurberiae weevils. In cotton 

 bolls the grandis weevils averaged 16.2 days and the thurberiae weevils 

 averaged 15.4 days. 



The total developmental period for females is slightly shorter than 

 for the males, which agrees with the observations at Victoria, Tex., 

 in 1913. The average developmental period is apparently a day or 

 more shorter at Tallulah than at Victoria in the same season. There 

 seems to be no difference of note in the records for the various years. 



In addition to these studies an experiment was conducted to 

 determine the relative length of the developmental period in squares 

 and bolls when the eggs were deposited by the same female. For 

 this purpose 11 pairs of bred grandis were mated on cotton squares 

 until they started normal deposition; then they were given squares 

 and bolls on alternate days and the eggs deposited in them were saved 

 for adult emergence. The comparison of the results is shown in 

 Table XXIV. 



