THE STATUS OF THE COTTON BOLL WEEVIL IX 1909. 11 



consequently obviated two important difficulties that attended the 

 use of Paris green; that is, the danger of burning the plants by large 

 applications and the difficulty in forcing the substance into the parts 

 of the plants where it would be taken up by the insect. Thus the 

 foundation was laid for very greatly increasing the mortality that 

 had previously been obtained from the use of another poison. 



In 1909 the State Crop Pest Commission of Louisiana had thirteen 

 experiments with powdered arsenate of lead, located at difi'erent 

 places, comprising over 46 acres. The poison was apphed at from 1 

 pound to 51 pounds per acre. In different experiments from one to 

 ten applications were made. In all but one of these experiments an 

 increased crop was obtained that resulted in a profit, after deducting 

 the expense incurred, which varied from a few cents to $2.3 per acre. 

 In the one experiment which did not result in a net profit an increased 

 yield of 121 pounds of seed cotton per acre was obtained. The very 

 large amount of poison used in this case (51 pounds per acre) involved 

 such an expense that this increased yield was not sufficient to offset 

 it. In the experiments in which from 10 to 23 pounds of the poison 

 per acre were used in from five to seven applications, the net profit 

 ran from $3.63 to $23.54 per acre. The most profitable amount of 

 the poison to be used seems thus to be indicated, although the con- 

 clusions from the preliminary work may be changed as the result of 

 future investigations. 



It is important to note that the very encouraging results obtained 

 by Mr. Newell were in experiments in which the application of the 

 poison was made either by one of his representatives or under this 

 representative's directions. A large part of the efficiency of pow- 

 dered arsenate of lead seems to be due to the thoroughness of the 

 application. It is therefore to be supposed that under the practical 

 conditions obtaining on plantations it may not be possible to obtain 

 as successful results as those in some of the experiments described. 



It does not detract from the high value of Mr. Newell's discovery 

 to state that all the experiments that have been performed indicate 

 most clearly that powdered arsenate of lead is not an absolute specific 

 for the weevil in the sense that it can be relied upon to the omission 

 or neglect of other means of control. The early fall destruction of 

 the cotton plants is undoubtedly a condition necessary to the suc- 

 cessful use of the poison. Likewise, the other steps in the system of 

 control advocated by the Bureau of Entomology are not minimized by 

 the importance of the present discovery. At most the poison merely 

 places another means of control at the command of the planter. 

 Everything indicates that it will be an important means. The system 

 of control in use has been to a certain extent a combination of expe- 

 dients for avoiding damage rather than of ways of actually killing the 

 weevils. In fact, the early fall destruction of the weevils by burning 



