81 



case that more than one larva develops. If two or more hatch in a 

 square, one is likely to destroy the others when their feeding brings 

 them together. They bite savagely at anything which irritates them, 

 and larvae have been found in the actual death struggle. Secondly, 

 should eggs be placed in squares which already contain a partly 

 grown larva, those hatching would likely find the quality of the food 

 so poor that they would soon die without having made much growth. 

 One Qgg will insure the destruction of the square, and a number of 

 eggs, could all the larvae live, would do no more. Therefore it is 

 plain that the possible number of offspring of a single female is increased 

 directly in proportion to the number of her eggs that she places one 

 in a square, and favorable food conditions for the larva are best 

 maintained by avoiding feeding upon squares in which eggs have 

 been deposited, and also by refraining from ovipositing in squares 

 which have been much fed upon. These habits of selection are, there- 

 fore, of the greatest importance in the reproduction of the weevil, 

 since they insure the most favorable conditions for the maturity of 

 the largest possible number of offspring. In other words, these habits 

 enable the weevil to do the greatest damage of which it is capable 

 while the cotton crop is u making." 



These habits are perhaps less strongly marked in the case of bolls, 

 though still plainly manifested. Feeding and ovipositing are common 

 in the same boll, but unless the infestation is very great indeed it 

 appears that only rarely is more than one egg placed in one lock, 

 though several are often deposited in the same boll. The number 

 deposited depends considerably upon the size of the boll. The smallest, 

 which have just set, receive but one, as do the squares, and these fall 

 and produce the adult weevil at about the same period as in the case 

 of squares. Bolls which are larger when they become infested are 

 often found to be thickty punctured and sometimes contain 6 or 8 

 larva?. The weevil seems to know when the food supply is sufficient 

 to support a number of larvae and deposits eggs accordingly. 



ACTIVITY OF WEEVILS IN DIFFERENT PARTS OF THE DAY. 



The 5 females used in these tests were kept in a field cage on pre- 

 viously uninfested plants, and examinations of their work were made 

 mostly at four-hour intervals from 6 a. m. to 6 p. m. The exact work 

 found was recorded upon tags attached to the squares themselves. 

 Temperature readings were taken at the same time as the observa- 

 tions. The results are most clearly presented in tabular form (p. 82). 

 16780— No. 51—05 -6 



