SEASONAL STUDIES OF INSECT CONTKOL. 



15 



hangs by a few threads and dries on the plant. (PL I, fig. 2 ; fig. 3, h.) 

 To these squares and bolls which thus hang, we have applied the 

 terms '^hanging squares" and '^hanging bolls." 



Tables II and III, which are arranged to show the monthly per- 

 centages of control by parasites, by predators, and by all insects, 

 illustrate the differences in the control of the weevil in the four 

 principal classes of infested material, namely, fallen and hanging dry 

 squares, and fallen and hanging dry bolls. 



A few words of explanation of these tables are necessary in order 

 to show what is meant by the different classes of mortality. It has 

 been found that a large number of stages are destroyed as eggs or 

 young larvse by the proliferation of the plant tissues. At the time 

 of the examination for mortality of the weevil, all evidence of the 

 weevils destroyed in these stages has disappeared; consequently the 

 percentages of mortality given in the following tables are the per- 

 centages of stages found which are killed by the causes enumerated, 

 and the mortality from proliferation is entirely ignored. 



Table II. — Monthly mortality of the boll weevil due to insects in fallen squares. 





Squares 

 exam- 

 ined. 



Stages. 

 foimd. 



Stages killed by- 



Percentage of stages killed. 



Month. 



Cli- 

 mate. 



Preda- 

 tors. 



Para- 

 sites. 



Total. 



Preda- 

 tors. 



Para- 

 sites. 



All 



insects. 



1906. 

 June 



4,476 



7,265 



19,305 



10, 709 



1,981 



3,831 

 4, 552 

 11,186 

 5,365 

 600 



1,797 

 1,676 

 2,828 

 1,475 

 205 



914 

 1,079 

 4,097 

 1,625 



133 



118 

 207 

 180 

 285 

 33 



73.8 

 65.1 

 63.5 

 63.0 

 61.8 



23.8 

 23.6 

 36.6 

 30.2 

 22.1 



3.1 

 4.7 

 1.7 

 5.4 

 5.6 



26.9 



July 



28.3 



August 



September 



38.3 

 35.6 



October 



27.7 







Totals and averages for 

 1906 



43,736 



25,534 



7,981 



7,848 



823 



65.2 



30.7 



3.3 



34.0 







1907. 

 June 



2,074 



5,192 



7,400 



150 



1,261 



3,608 



5,058 



93 



339 



778 



2,156 



90 



198 



433 



1,372 







76 



133 



155 



1 



48.6 

 37.2 



72.8 

 97.7 



15.6 



11.9 



27.1 







7.0 

 3.8 

 3.0 

 1.0 



22.6 



July . . 



15. 7 





30. 1 



November 



1.0 







Totals and averages for 

 1907 



14,816 



10,020 



3,363 



2,003 



365 



57.1 



19.9 



3.7 



23.6 







1908. 

 May 



100 



7,808 

 7,437 

 1,941 

 7,189 

 9,678 

 604 



56 

 5,285 

 4,690 

 1,208 

 3,894 

 5,342 

 369 



4 

 1,169 



1,047 

 540 

 578 

 807 

 90 







866 

 902 

 294 

 815 

 289 

 1 



2 

 324 

 219 



63 

 136 

 659 



88 



10.7 

 44.6 

 46.2 

 74.2 

 39.2 

 32.8 

 51.1 





 16.4 

 19.2 

 24.3 

 20.9 

 5.4 

 2.7 



3.5 

 6.1 

 4.7 

 5.2 

 3.5 

 12.3 

 22.6 



3.5 



June 



22.5 



July . 



23.9 



August 



29.5 





24.4 



October 



17.7 



November 



25.3 







Totals and averaees for 

 1908 V 



34,757 



20,844 



4,235 



3,167 



1,491 





 131 



38 

 1 



42.7 







45.1 



39.9 



6.8 



15.2 







11.7 



14 9 



1.4 



7.1 





 3.0 

 1.3 

 .3 



22.3 







1909. 

 January 



50 



7,677 



5,507 



750 



23 



4,334 



2,866 



364 







1,318 



680 



19 







507 



428 



5 







July 



14.7 



August 



15.2 



September 



1.7 







Totals and averages for 

 1909 . . 



13,984 



7,587 



2,017 



940 



170 



41.2 



12.4 



2.2 



14 6 







