BIOLOGY OF ARIZONA WILD COTTON WEEVIL. 11 



From this it is seen that more weevils were observed on cotton 

 and there was also more feeding on this plant than on Thurberia 

 in the course of the entire experiment. At the very beginning 

 what seemed to be a preference in favor of Thurberia was noted, but 

 this disappeared later. 



On the 4th of August 13 females and 12 males were removed from 

 cells in Thurberia bolls collected in the Santa Rita Mountains in 

 December, 1913, and kept almost entirely without food (cotton 

 leaves fed only once) until August 7. They were then placed in a 

 cage with Thurberia and cotton plants, both bearing buds and bolls. 

 The experiment was continued until September 17 though the last 

 feeding was noted September 11. Throughout this time a slight 

 preference in favor of Thurberia was maintained and the summary 

 of observations is as follows: 



Cotton attacked records. . 7 



Thurberia attacked do 13 



Weevils on cotton, 3 male, 4 female, 1 of sex not determined. total. . 8 

 Weevils on Thurberia: 7 male, 11 female, 1 of sex not deter- 

 mined total. . 19 



These two tests of unfed weevils total as follows: 



Records. 



Cotton attacked 31 



Thurberia attacked 32 



Weevils on cotton 32 



Weevils on Thurberia. 38 



From these figures it is quite evidently useless to attempt to credit 

 the weevils with a choice for either plant when unfed before testing. 



WEEVILS FED UPON COTTON SQUARES BEFORE TESTING. 



On the 24th of August 12 weevils of each sex were removed from 

 the hibernation cells in Thurberia bolls collected in the Santa Rita 

 Mountains December 4, 1913. These were fed upon cotton squares 

 from this date until August 31 and then placed in a cage with cotton 

 and Thurberia plants bearing buds and bolls. This test was con- 

 tinued until September 27 and the feeding continued until that date. 



For the first few days a slight preference in favor of cotton was 

 shown, but this soon disappeared and the feeding was much the same 

 on the two plants for the remainder of the experimental period. 

 The summary of observations is as follows : 



Attacking cotton . records. . 9 



Attacking Thurberia do 7 



Weevils on cotton: 8 male, 6 female, 1 sex not determined, .total.. 15 



Weevils on Thurberia : 11 male, 6 female, 1 sex not determined . do . . . 18 



From this feeding it is evident that, while the feeding upon cotton 

 squares for the first few days after emergence may have caused a 

 slight preference in favor of cotton plants early in the test, this did not 

 last more than a very short time and then no preference was shown. 



