28 



BULLETIN 926, U. S. DEPARTMENT OF AGRICULTURE. 



period of 31.2 days. A total of 298 weevil days was required by the 

 10 female weevils bred from long-staple cotton bolls, or an average 

 period of 29.S days from egg to adult. The sea-island cotton bolls 

 produced 30 male weevils that required 953 weevil days from egg to 

 adult, or an average developmental period of 31.7 days. A total of 

 18 female weevils bred required 623 weevil days, or an average period 

 of 34.6 da} 7 s for development from egg to adult. (Fig. 12.) 



Since the bolls had probably 

 been punctured from 5 to 7 days 

 before they were bagged, it is evi- 

 dent that the developmental 

 period of the boll weevil in green 

 cotton bolls is approximately 35 

 to 40 days under the most favor- 

 able summer temperatures and 

 longer during the fall months. 

 Howe ° states that the develop- 

 mental period of the boll weevil 

 in green upland cotton bolls at 

 Tallulah, La., under insectary 

 conditions, was 16.2 days. At 

 Madison, Fla., the developmental 

 period of the boll weevil in green 

 cotton bolls under actual field 

 conditions more than doubles 

 Howe's record. 



Fig. 12.— Four cavities in which four 

 boll weevils were reared in a sea- 

 island cotton boll, Madison, Fla. 



FECUNDITY OF THE BOLL WEEVIL IN UPLAND AND SEA-ISLAND 



COTTON BOLLS. 



Throughout the season of 1918 attempts were made to secure rec- 

 ords of the fecundity of the weevil in green cotton bolls. More than 

 200 pairs of weevils were under observation at different times during 

 the season. In no case were clear and concise records secured for 

 individual weevils. For some peculiar reason the females did not 

 oviposit freely in the green cotton bolls under insectary conditions. 



PREFERENCE SHOWN BY FEMALE WEEVILS FOR OVIPOSITION IN SEA-ISLANI> AND 



UPLAND COTTON FRUIT. 



An experiment to determine the preference by the boll weevil for 

 deposition was made by confining six female weevils over upland 

 and sea-island cotton fruit. The female weevils were confined in a 

 large battery jar on moist sand. Fresh squares and bolls of both 

 sea-island and upland cottons were placed in the jar each morning 



» Howe, R, W. Studies of the Mexican Cotton Boll Weevil in the Mississippi Valley, 

 r. s. Dept, Agr. Bui. 3B8, p. 28, 1916. 



