BIOLOGY OF THE MEXICAN COTTON BOLL WEEVIL. 



15 



THE DEVELOPMENTAL PERIOD OF THE BOLL WEEVIL UNDER 



FIELD CONDITIONS. 



Although it has been known that the factors of temperature and 

 humidity influence the development of the boll weevil, and that labo- 

 ratory breeding methods are more or less artificial, the exact differ- 

 ence between the life history of the weevil under field conditions and 

 in the laboratory has never been determined. 



In the experimental work at Madison, Fla., in 1918, it was found 

 that the boll weevil in the field was requiring a considerably longer 

 period for development than had been expected. Records tabulated 

 by Hunter and Pierce s showed that the length of the developmental 



Fig. 5. — Cages used in the oviposition studies of the boll weevil under field conditions, 



Madison, Fla. v 



period varied with the length of time the infested squares hung on 

 the plant after egg puncture. The Madison studies fully corrob- 

 orate this statement. 



The field-breeding records were secured under conditions which 

 most nearly simulate nature. A large cage was placed over a cotton 

 plant on which there were no infested squares (fig. 5). A single 

 female or a male and female were liberated in the cage with the non- 

 infested squares. On the second day if any squares were infested 

 these were tagged (fig. 6) and the cage and weevil were then removed 

 to a fresh cotton plant from which all infested squares had been 

 removed. Thus day by day the weevil's maximum oviposition capa- 

 city was obtained and the infested squares remained on the plant 



8 Hunter, W. D., and Pierce, W. D. The Mexican Cotton Boll Weevil : A Summary of 

 the Results of the Investigation of this Insect up to December 31, 1911. Senate Docu- 

 ment 305 (U. S. Dept. Agr., Bur. Ent. Bui. 114). 188 p., 22 pi., 33 figs. 1912. 



