12 



BULLETIN 344, U. S. DEPARTMENT OF AGRICULTURE. 



WEEVILS FED UPON THURBERIA BEFORE TESTING. 



On August 24 another lot of weevils (11 males and 12 females) 

 were removed from cells in Thurberia bolls collected in the Santa 

 Rita Mountains December 4, 1913. These weevils were fed upon 

 Thurberia buds and leaves until August 31 and then were placed 

 in a cage with Thurberia and cotton plants, both bearing squares 

 and bolls. Here the initial feeding showed a preference for Thur- 

 beria, but this was lost within a few days and the feeding became 

 almost equal on the two plants. The test was continued until 

 September 17 and feeding lasted until that time. The summary of 

 observations for this lot is as follows : 



Attacking cotton records. . 7 



Attacking Thurberia do 6 



Weevils on cotton: 5 male, 7 female total. . 12 



Weevils on Thurberia: 7 male, 11 female do 18 



SUMMARY OF ALL TESTS. 



The summary of the results of the various experiments just detailed 

 is given in Table I. 



Table I. — Relative attraction of cotton and Thurberia for weevils. 





Cotton. 



Thurberia. 





Plants 

 attacked. 



Weevils. 



Plants 

 attacked. 



Weevils. 



"Food before starting test. 



Male. 



Fe- 

 male. 



Sex 



not 

 deter- 

 mined. 



Total. 



Male. 



Fe- 

 male. 



Sex 



not 

 deter- 

 mined. 



Total. 





31 

 9 



7 



6 

 8 

 5 



25 

 6 



7 



1 



1 



32 

 IS 

 12 



32 

 7 

 6 



10 

 11 



7 



25 

 6 

 11 



3 

 1 



38 





18 





18 







Total 



47 



19 



38 



2 



59 



45 



28 



42 



4 



74 







From this table it is seen that, while the cotton plants were at- 

 tacked slightly more than the Thurberia, more weevils were observed 

 on the latter. It is interesting to note that in the total of the ob- 

 servations of the weevils on both plants males were noted 47 times 

 and females 80 times. As the weevils used were very nearly equally 

 divided as to sex (49 males and 51 females), this seems an instance 

 of the greater activity of the females. 



These cage tests seem to indicate that unfed hibernated Thurberia 

 weevils display no preference for either plant, while those fed on 

 either plant exclusively for a few days after emergence will at 

 first favor that plant slightly when offered a choice, but will 

 soon feed equally on both. From this it would seem that neither 

 plant has the power to attract the weevils away from the other, 

 but later observations made in the field are rather contradictory to 

 this. The field cotton at the ranch this season was repeatedly at- 

 tacked by the weevils, and, while there was considerable injury to 

 the squares and bolls on this cotton, only two bolls were attacked on 



