89 



almost certainly abundant. The conditions named form the most 

 conspicuous indications of practically total infestation. During the 

 season of 1903 it was found that a condition of total infestation was 

 reached some time between August 1 and 20 in most fields within the 

 infested area. This condition is, as a rule, coincident with the appear- 

 ance in large numbers of weevils of -the fourth generation. The exact 

 time will var}^ in different seasons, and even in adjacent infested fields, 

 because of varying conditions. 



Not onl^^ is the maximum number of weevils present in the field in 

 midsummer, but their capacitj' for injury is also greatest at that 

 time. Practically all of the crop that will be made must have been 

 set before this time. After this bolls will form only by accident. 



A large series of examinations made by Messrs. Harris and Morrill 

 at Calvert, Tex., shows the very rapid increase in the percentage of 

 infested squares which usually takes place a few weeks earlier than 

 it did in 1903. The figures given in each column in the table show 

 also the closeness with which the weevil activity kept pace with the 

 formation of squares after the j)eriod of maximum infestation had 

 once been reached. The general influence of climatic conditions may 

 be seen by a comparison of the last two columns in the table, but this 

 point would be much more clearly shown by a series of examinations 

 made during the first half of the growing season, at whicli time tem- 

 perature and moisture would have greatest influence upon weevil 

 development and injury. One hundred squares were picked promis- 

 cuously in each block for the determination of the percentages given 

 in the columns for these 34 blocks, thus making a total of 17,000 

 squares examined. 



Table XXIV. — Study of the infestation of cotton fields at Calvert, Tex. 



Time of record. 



1903. 



August 15-17 _ 



September 3-4 



September 14-17 . . 



October 1-3 



October 22-24 



Block. 



a5 

 la) 



94 

 91 

 90 



5 6 



63 60 

 97 9S 



10 11 12 20 21 22 



