10 BULLETIN 731, U. 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 
Fiac. 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 nin 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- 
tions 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 
