RETENTION OK S I lEDDINlJ OF 1 N I' EST HI ) lOK.MS. 33 



ants caused a luoiialitv of [A\ jxm- ccmU aiiioiiLr liaiiLriiiLT forms and '2.1. \ 

 j)er cent anionic: fallcMi forms, wliilc })arasi(es caused a mortalit \- of 

 2.2 per cent amoni;- lian_ii:ini:: forms and only 2.1 per cent amoiiLT fallen 

 forms. 



The conclusions may also l)e drawn from a study of the j)roj)ortion 

 of weevil stai^es found dead in onrh class of forms, in comiection with 

 the factors causinij: death and the propoi'tion of foj-ms lo \\cc\il 

 sta.<2:es in each class examincMl. In (his way it apjx'ars (hat ihc low- 

 est total mortality was found in the han^iniz; bolls which diicd u|)on 

 the plant, beiniz: in this case 'M)A ])er ciMit. For fallen l)olls this jx'r- 

 centaij:e was 3o.4, in haui^injj; s(piar(\s there was a mortality of 52. (i, 

 while in fallen squares it amountcMl to 60.8 per cent. Taking next a 

 comparison of hanixin*^ and fall(>n forms, it appears that there was an 

 advantaire ilurin^r the s(Mison of 1906 of 16.2 per cent greater total 

 mortality among the fallen forms. 



As to the factors which were most effective in producing this mor- 

 tality, it appears that among hanging forms ants prochiced 46.5 per 

 cent of the total mortality found, while in fallen forms they were 

 responsible for 53.2 per cent of the total mortality. It is evident, 

 therefore, that in either hanging or fallen forms Solenopsis geminata 

 was the most important summer factor in 1906 in controlling the 

 weevil. When it is considered that a large majorit}^ of the infested 

 forms fall, it becomes still more certain that the efl'ectiveness of the 

 factors naturally tending to control weevil multiplication is greater 

 when the infested forms are shed than when they are retained by tlie 

 plant. 



From these data it appears that it is more desirable that plants 

 shed their infested forms completely and quickly after the infesta- 

 tion takes place than that they should retain them, allowing the 

 weevil stages therein to develop under the smaller influence of natural 

 control to whicli they w^ould then be subjected. 



MORTALITY IN BOLLS VERSUS SQUARES. 



It should be stated that in these examinations no attempt was 

 made to determine the mortality among weevil stages in large bolls 

 which continued their development in spite of the weevil attack. 

 In such bolls it is obvious that heat or dr^^ing can have had little if 

 any effect upon the weevil stages. Ants do not enter green, growing 

 l)olls, though they fre((uently destroy w^eevil stages w-hich become 

 more easily exposed to their attack through the opening of the bolls. 

 Instances have been found of parasitism of weevil stages in large 

 bolls. Proliferation is, however, an active factor which has been 

 found in the examination of more than 12,000 locks to produce an 

 increase in mortality of wecn'il stages amounting to between 6 and 7 

 per cent. 



1157.^— P.ul. 74—07 .S 



