BIOLOGY OF THE MEXICAN COTTON BOLL WEEVIL. 25 



of the same series required 718 weevil days, or an average develop- 

 mental period from egg to adult of 21.8 days. The developmental 

 period for both sexes under field conditions averaged 21.1 days from 

 egg to adult. 



The total percentage of the infested squares producing adult 

 weevils could not be determined, as a considerable number of the 

 infested squares under observation were detroyed by ants, Sole- 

 ?wpsis sp. (fig. 10). 



COMPARISON OF THE DEVELOPMENTAL PERIOD OF THE IMMA- 

 TURE STAGES OF THE BOLL WEEVIL UNDER FIELD AND IN- 

 SECTARY CONDITIONS. 



The results of the breeding experiments under outdoor insectary 

 conditions, conducted primarily to check the field breeding records, 

 are tabulated and summarized in Table XIII. The average develop- 

 mental period under insectary conditions for the hibernated and 

 first-generation weevils in upland cotton squares was 14.5 days. 

 The developmental period of the progeny produced by first genera- 

 tion weevils in long-staple upland and sea-island cottons was 14.2 

 and 13.7 days, respectively. There is little if any difference in the 

 length of the developmental period of the weevils bred in the 

 three types of cotton squares under insectary conditions. A total 

 of 1,148 weevils which required 16,568 weevil days or an average 

 period of 14.3 days for development under insectary conditions is 

 recorded for the three types of cotton. 



The developmental period of the immature stage of the boll weevil 

 under normal field conditions on short-staple upland, long-staple 

 upland, and sea-island cottons is presented in Table XIV. The male 

 weevils bred in upland cotton squares required 21.7 days for develop- 

 ment from egg to adult and the females of the same series required 

 a slightly longer period — 22.33 days. A total of 323 weevils bred 

 in upland cotton squares under normal field conditions required an 

 average period of 21.9 days for development from the time the egg 

 was deposited to emergence of the adult weevil. 



In sea-island cotton squares 92 male weevils required 2,006 weevil 

 days, or an average period of 21.8 days, for development from egg 

 to adult. The 75 female weevils bred from the same source required 

 1,651 weevil days or an average period of development of 22 days. 

 Both sexes required an average developmental period of 21.9 days 

 from egg to adult. 



On long-staple upland cotton 35 male weevils bred in squares 

 under field conditions required 726 weevil days or an average period 

 of 20.7 days for development of the immature stages. The 26 female 

 weevils required 549 weevil days or an average period of 21.8 days 

 for development. Both sexes bred in long-staple upland cotton 

 squares required an average period of development of 20.9 days from 

 egg to adult. 



