CONTROL OF BOLL WEEVIL IN MISSISSIPPI DELTA. 3 



connection was the use of the bag-and-hoop as a weevil collector. 

 This semimechanical method, which has been explained in detail in 

 the earlier bulletin, proved to collect more weevils in less time than 

 did hand picking, and as an additional advantage gathered a con- 

 siderable number of infested squares and bolls during the course of 

 the shaking operation. As it was so well adapted to the type of 

 labor available and as it considerably reduced the amount of labor 

 required, this method appeared to give the greatest promise of suc- 

 cess. Consequently the investigations of 1916, which largely em- 

 ployed the bag-and-hoop method of collection, were aimed at secur- 

 ing information on the exact degree of control exerted by its use in 

 the field under varying conditions. 



LINES OF INVESTIGATION IN 1916. 



The experiments of 1916 may be divided into three more or less 

 distinct lines of investigation. These were: (1) Plat tests under 

 field conditions to determine the degree of weevil control produced 

 by the operation of the bag-and-hoop for different periods at various 

 time intervals between pickings; (2) intensive studies on the relation 

 of the time interval between the pickings to the proportion of the 

 infested forms collected in the bag; and (3) studies on the efficiency 

 of certain mechanical collectors. 



TIME INTERVAL BETWEEN BAG-AND-HOOP COLLECTIONS IN RELATION 

 TO PROPORTION OF INFESTED FORMS SECURED. 



As has been stated, one of the favorable features attending the use 

 of the bag-and-hoop as a means of collecting weevils was the collec- 

 tion of the infested squares and bolls while shaking the plants for the 

 weevils. Thus this operation to some extent combined the results 

 secured from two operations — (1) hand picking of weevils and (2) 

 hand picking of infested forms. However, in attempting to outline 

 some scheme for the practical use of the bag-and-hoop in the field 

 it was necessary to know just what proportion of the forms fall- 

 ing to the ground because of weevil injury would be collected at 

 different time intervals between pickings. In other words, it seemed 

 desirable to find just what time interval would be necessary to secure 

 the largest proportion of the infested squares and still be feasible for 

 use. Indirect information on this score was of course secured from 

 the general field tests of the use of this method of control; but, in 

 addition to these, an intensive study was conducted by Mr. Williams 

 on Eureka plantation, near Tallulah, La. The idea of this study was 

 not so much to secure information on the actual degree of weevil 

 control exerted by this operation in the plats under observation, but 

 to secure information on the forms collected in the bags and the 



