HIBERNATION OF THE MEXICAN COTTON BOLL 



WEEVIL. 



ENTRANCE INTO HIBERNATION. 



In the stud}" of hibernation of the Mexican cotton boll weevil 

 (A?ithonomus grandis Boh.) we shall first consider the factors affect- 

 ing the abundance of weevils which may enter hibernation, the 

 dependence of the number of weevils present upon preceding con- 

 ditions of food supply, the climatic conditions accompanying or 

 producing the beginning of hibernation, and other biological facts 

 which may be of interest or value in connection with this division 

 of the subject. 



SUPPLY OF WEEVILS TO ENTER HIBERNATION. 



The common name "cotton boll weevil," which is uniformly 

 applied to this insect, may be in part at least responsible for a mis- 

 leading impression in regard to the most common point of attack 

 and place of development of this weevil. The common name was 

 first applied because of the fact that in the first recorded case of this 

 insect attacking cotton the specimens were found in bolls. It is a 

 fact, however, that by far the greater number of weevils to be found 

 in any field at any season of the year have really developed within 

 the buds or squares rather than within the bolls. In the first place, 

 it is perfectly evident that during the entire growing season of the 

 plant, in the infested area, probably not much more than 10 per cent 

 of the squares which form ultimately produce bolls. For this reason 

 the weevils find opportunities for reproduction many times greater 

 in squares than in bolls. In the second place, a careful study of the 

 habits of the weevils shows that they prefer squares both for feeding 

 and for reproduction. In the third place, the average period required 

 for development in squares is only one-half to one-third as great as 

 it is in bolls which become more than one-half grown. These three 

 considerations insure a far more rapid and abundant multiplication 

 of individuals through the medium of squares than through bolls. 

 Wherever weevils have been present in average abundance at the 

 beginning of the season, unless they have been unusuall}^ checked 

 by climatic conditions unfavorable to their development, a condition 

 of total infestation of squares is usually reached between August 1 



11 



