14 



BULLETIN 926, U. S. DEPARTMENT OE AGRICULTURE. 



THE AVERAGE DEVELOPMENTAL PERIOD OF THE COTTON BOLL 

 WEEVIL UNDER OUTDOOR INSECTARY CONDITIONS. 



The data on the average developmental period of the boll weevil 

 under outdoor insectary conditions for sea-island and upland cottons 

 are presented in Table VII. These observations extended over a 

 period of time beginning on May 26 and ending on September 10. The 

 maximum developmental period of any weevil from egg to adult was 

 18 days and the minimum period 11 days. On upland cotton 506 

 male weevils bred in the insectary required a total of 7,568 weevil 

 days, or an average period from egg to adult of 14.62 days. A total 

 of 347 female weevils bred under insectary conditions required an 

 average developmental period of 14.8 days. The average period of 

 development for the immature stages bred in upland cotton squares 

 is shown to be 14.91 days. 



On sea-island cotton 150 male weevils required 2,214 weevil days 

 from egg to adult, or an average developmental period of 14.82 days. 

 A total of 101 female weevils, bred in sea-island cotton squares, re- 

 required 1,550 weevil days, with an average period of 15.06 days for 

 development from egg to adult. There is practically no difference 

 in the time required for development of the immature stages of the 

 boll weevil in sea-island and upland cotton squares. 



Table VII. — Total developmental period of the ooll weevil under insectary con- 

 ditions, Madison, Fla., 1918. 





Larval 

 food. 



Oviposition 

 period. 



Males. 



Females. 



Both sexes. 



Source of weevils. 



Num- 

 ber 

 bred. 



Wee- 

 vil 

 days. 



Aver- 

 age 



peri- 

 od. 



Num- 

 ber 

 bred. 



Wee- 

 vil 



days. 



Aver- 

 age 



peri- 

 od. 



Total 

 num- 

 ber 

 bred. 



Total 

 wee- 

 vil 

 days. 



Aver- 

 age 

 de- 

 velop- 

 ment - 



al 

 peri- 

 od. 



Upland cotton: 

 Hibernated... 



Do 



Cotton 

 square. 



May 26-July 27 



May 29- July 23 

 June 14- Aug. 15 



July 17-SeptS. 



201 



57 

 208 



40 



2,931 



816 

 3,183 



638 



Days. 

 14.09 



13.4 

 15.3 



15.7 



126 



41 

 133 



47 



1,812 



564 

 2,029 



742 



Days 

 14.38 



13.7 

 15.2 



15.9 



327 



98 

 341 



87 



4,726 



1,380 

 5,218 



1,380 



Days. 

 14.4 



14.08 



First genera- 

 tion. 



Second gener- 

 ation, i 



...do 



...do 



15.38 

 15.8 



Total.. 



506 



7,568 



i4.62 



347 



5,147 



iiY ' 



853 



12, 704 











14 91 





Cotton 

 square. 



May 26- July 20 



May 25-July 18 

 June21-Aug.l5 



July 11-Sept. 4 













Sea-island cotton: 

 Hibernated... 



Do 



67 



34 

 33 



16 



965 



490 



498 



261 



13.5 



14.4 

 15.09 



16.3 



46 



15 

 15 



25 



689 



220 

 249 



392 



13.46 



14 6 

 16.6 



15.6 



115 



49 



48 



41 



1,654 



690 

 746 



653 



14.3 

 14.08 



First genera- 

 tion. 



Second gener- 

 ation. 



...do 



...do.... 



15.5 

 15 9 



Total 



150 



2,214 



14.82 



101 



1,550 



15.06 



253 



3,743 









14.94 





1 

















