346 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



experiments in which some of the cages were covered so as to prevent the 

 formation of dew on the plants and in other cages the dew was allowed 

 to form on the plants. In each case the plants were dusted in the same 

 manner with calcium or lead arsenate. A slightly higher mortality was 

 obtained in cages where the dew was not allowed to form. 



Circular 38 of The Alabama Polytechnic Institute by W. E. Hinds 

 gives briefly the results of tests conducted by the writer under the 

 direction of Dr. Hinds during the summer of 1918. These were labora- 

 tory and field tests in which moisture was applied or allowed to form 

 on the plants in one case and excluded in another. Here a slightly high- 

 er mortality was obtained on poisoned plants where the moisture was 

 excluded and exclusion of moisture from the checks had no effect upon 

 the mortality. 



In view of the difference of opinion upon the question of whether 

 moisture is essential for the weevil to ingest the poison, the writer con- 

 sidered it worth while to conduct further experiments upon the problem. 

 Accurate information upon this question is essential in applying control 

 measures for this insect. 



Location of Experiments and Materials Used 

 The experiments here given were conducted at Valdosta, Georgia 

 at the Sea Island Experiment Station of the Georgia State Board of 

 Entomology during the summers of 1920 and 1921 . The cages used were 

 3x3x4 feet and 4x4x6 feet. Vigorously fruiting plants were selected 

 for caging and the bottom of the cages was covered with heavy paper 

 so as to make the dead weevils readily seen. The calciimi arsenate used 

 was of the chemical constitution recommended for cotton dusting. A 

 fairly heavy dosage of poison (about 10 pounds per acre) was applied to 

 the caged plants. 



Experiments Comparing Mortality from Feeding during the 

 Period of the Day in which there is Dew on the Plant with 



THE Period during which the Plant is free from Dew 

 These experiments were carried out in a manner somewhat different 

 from those previously conducted in testing the relation of moisture to 

 ingestion of the poison by the weevil. Here, mortality, from feeding 

 during the period in which the dew remains on the plant, was compared 

 with mortality from feeding during the period in which there is no dew 

 on the plant. Thus the mortality among weevils which fed upon poison- 

 ed plants from 6 p. m. to 8 a. m. was compared with the mortality among 

 weevils which fed upon poisoned plants from 8 a. m. to 6 p. m. The 



