62 



NATURAL CONTROL OF THE COTTON BOLL WEEVIL. 



of weevil stages found in this class of forms being somewhal more 

 than 60 per cent of the total. Eastern Texas, southern Texas, and 

 western Louisiana seem to have profited most by the work of the ants 

 in fallen squares, and those same sections show the highest percentages 

 of ant work in fallen bolls, as might naturally be expected. 



The wide diversity of conditions under which the ants successfully 

 attack the weevil is another one of the encouraging features shown by 

 this work. It proves in a very reassuring way the general distribul ion 

 of this species of Solenopsis and their activity in destroying weevil 

 stages in every class of forms and in all parts of the infested area. 

 The value of the work which they do in restraining the weevil multi- 

 plication can not be estimated. Their work henceforth will be more 

 fully appreciated and a careful study will be made of the life history 

 of the species and of the possibility of producing an increase in its 

 efficiency. 



SECTIONS PROFITING MOST BY NATURAL CONTROL. 



Still another arrangement of this same series of results will show 

 most plainly a comparison of the total mortality in the four classes of 

 forms for each of the six. sections into which the localities have been 

 grouped. In Table XIII are shown the general results of the 

 examinations. 



Table XIII. — Comparison of total mortality results according to section. 



Section. 



Western Louisiana . 



Eastern Texas 



Southern Texas 



Central Texas 



Northeastern Texas 

 Southwestern Texas 



Total 

 forms 

 exam- 

 ined. 



10, 999 

 12,933 

 37, 080 

 16, 724 

 7,172 

 2,048 



>,956 



Weevil stages alive. 



Larva. 



576 

 1,374 

 2,311 

 865 

 430 

 396 



5,952 



Pupa, 



Adult. 



Pres- 

 ent. 



672 I 



1,665 

 923 

 376 

 126 



365 

 259 

 ,033 

 462 

 258 

 30 



4.645 2,407 



Em- 

 erged. 



,070 

 397 



,407 



686 



334 



48 



3,942 



Weevil stages dead 

 from heat or drying. 



Mortality from heat, 

 etc., by stages. 



Larva. Pupa. Adult. Larva. Pupa. Adult. 



293 

 492 

 4,812 

 820 

 137 

 62 



603 

 131 



77 

 3 



105 

 24 

 155 

 105 

 32 

 3 



Perct: 



50.9 

 35.8 

 67.6 

 48.7 

 24.2 

 1.6 



P.ct. Pcrct. 



20. 5 7. 3 



8.6 3.7 



6.0 

 8.4 

 5.1 

 3.8 



26.6 

 12. 4 

 17.0 

 2.4 



6,616 1,018 424 52.6 18.0 



6.3 



Section. 



Western Louisiana . . 



Eastern Texas 



Southern Texas 



Central Texas 



Northeastern Texas . 

 Southwestern Texas . 



Killed by heat 

 or drying. 



Num- 

 ber of 

 stages. 



526 

 592 

 ,570 

 ,056 

 246 

 68 



8,058 



Per cent 

 of total 

 stages 

 found. 



10.3 

 11.1 

 28.3 

 18.2 

 11.1 

 8.1 



20. 7 



Killed by ants. 



Killed by 

 parasites'. 



Number 



of stages, 



1,526 

 1,465 

 5,921 

 1,137 

 376 

 117 



Per I 

 cent of Num- 



total berof 

 stages stages. 

 found. 



29.9 

 27.4 

 30.0 

 19.8 

 16. 9 

 13.9 



156 



155 



811 



443 



86 



34 



Per 



cent of 

 total 

 stages 

 found. 



Total 

 number 

 of weevil 



stages 



found. 



3.0 

 2.9 

 4.1 

 7.S 

 3. 9 

 4.0 



Total 

 per cent 

 of mor- 

 tality 

 from 

 throe 

 causes. 



Rank 

 of sec- 

 tion in 



per- 

 cent- 

 age of 



mor- 

 tality. 



5.117 

 5.339 

 19.674 

 5.799 

 2 222 

 '840 



43. 2 

 41.4 

 62.6 



45. 5 



31.9 

 26. 



.10.542 



27.0 1,685 



3S.991 



