10 BULLETIN" 731, L T . S. DEPARTMENT OF AGRICULTURE. 



the effect of the single application was so pronounced that it seemed 

 unnecessary to repeat it. The weevils had been so reduced that only 

 36 per cent of the squares were punctured, and although thousands of 

 weevils were being bred out from the squares on the ground or were 

 coming in from other plantations every day, it was still obvious that 

 the weevils would greatly reduce their attack on the bolls until they 

 had caught up with the squares then present, and that this period 

 would be long enough to allow the bolls to become sufficiently hard- 

 ened to avoid weevil damage. Owing to the necessity of poisoning 

 considerable areas in this case and to the inability to leave unpoisoned 

 plats as checks, it was of course impossible to determine the exact 



Fig. 7.— View down center of check plat, Isola Cut No. 1, on October 26, 1917, showing cotton available 

 for second picking; Scott, Miss. For comparison with figure 8. 



benefit derived from the treatment. Rough comparisons, however, 

 based on yields of surrounding cuts, made it obvious that a consider- 

 able gain had been secured and it was evident that the poisoning was 

 a very profitable operation. 



LABORATORY AND OTHER EXPERIMENTS. 



Numerous other field experiments might be detailed to add weight 

 to the results secured, but the ones described have been selected as 

 illustrating the different methods followed and the different condi- 

 tion- experienced, and are surely sufficient to illustrate the effective- 

 ness of the poison. In addition to these field tests a number of 

 laboratory studies were conducted at the same time to check the 



