62 



with the Cuban cotton, which was planted late and began to square 

 during the latter part of August. For the purpose of this comparison, 

 both the several varieties and the various plots of the American cotton 

 will be considered together, as no evidence of preference was found 

 among them. 



In making a comparison of the results three elements must be con- 

 sidered for each variety of cotton: First, the number of plants of each 

 variety; second, the number of daj's during which each kind was 

 under observation; third, the total number of weevils found on each 

 class of cotton. The elements of numbers of plants and time under 

 observation may be expressed by the product of those two factors 

 forming a term which we may call "plant-days." The total number 

 of weevils found upon any class of cotton divided by the number of 

 ; ' plant-days '' will give the average number of weevils attracted by 

 each plant for each day, and these numbers furnish a means of direct 

 comparison and show at a glance the average relative attractiveness 

 of each class of cotton. The following table presents these results in 

 comparable form: 



Table XIII. — Relative attractiveness of various cottons. 





Num- 

 ber of 

 plants. 



Total. 



Average. 





Class of cotton. 



Plant- 

 days. 



Wee- 

 vils 

 found. 



In- 

 fested 

 squares 



Weevils 

 per plant 

 per day. 



Infested 

 squares 

 per wee- 

 vil. 



Relafive 

 attract- 

 iveness. 



1903. 



62 



4,920 



287 



3, 507 



0.058 + 



12.2+ 



1.0 







Cuban 



Sea Island 



5 ! 120 

 8 552 

 8 808 



11 



64 



207 



136 



1,089 

 2,013 



.092- 

 .116- 

 .256+ 



12.4- 

 17.0 + 



9.7 + 



1.6+ 

 2.0 



4.4+ 







Total of 3 non- American cottons. 



21 ; 1,480 



282 



3,238 



.191- 



11.5- 



3.3- 



1904. 



60 

 5 

 4 



3,780 

 315 

 252 



346 

 117 



102 





.0914 

 .371+ 

 .405- 





1.0 







4.0 







4.4 + 









An examination of these figures shows that American Upland cotton 

 is less subject to the attacks of the weevil than any of the others, and 

 that Egyptian (Mit Afifi) is by far the most susceptible. The differ- 

 ence in degree is most plainly shown in the column of "relative 

 attractiveness." It would certainly seem difficult to formulate a 

 stronger argument for the cultivation of American cottons alone within 

 the weevil-infested district than is presented by these figures. The 

 weevils gathered so thickly upon the Egyptian cotton that "the plants 

 could not produce sufficient squares to keep ahead of the injury, and 

 therefore the average number of infested squares for each weevil is 

 only three-fourths as great with that variety as with less infested 

 kinds, but the average injury to each square was greater than with 

 any other. 



