2 BULLETIN 344, U. S. DEPARTMENT OF AGRICULTURE. 



the two forms to interbreed very readily, however, thus demon- 

 strating their very close relationship. 



The biology of this weevil as studied at Victoria has been discussed 

 in two papers. 1 



In the spring of 1914 the writer was stationed near Tucson, Ariz., 

 where he studied the Thurberia weevil and its host plant under their 

 natural conditions. These studies consisted of biological investio-a- 

 tions similar to those conducted in Texas as well as the consideration 

 of the possible and probable economic importance of the weevil in the 

 arid West. The economic phases of the problem have been dealt with 

 in another report, 2 so they will be only very briefly mentioned hi the 

 present paper. 



The principal object of this report is to afford a comparison of the 

 life functions of the weevils as performed by: (1) Texas cotton weevils 

 at Victoria, Tex.; (2) Arizona Thurberia weevils at Victoria, Tex.; 

 and (3) Arizona Thurberia weevils in Arizona. The first two subjects 

 have already been covered in the papers previously mentioned and 

 the last is discussed in the present paper. By a proper consideration 

 of the activity and adaptability of the different forms of weevils 

 under the same environmental conditions and of the same form of 

 weevil under the different conditions it is possible to determine much 

 of importance concerning the ex act^ relation of the two varieties and 

 the extent of variation and adaptation to be expected from each. 



For the Arizona studies a camp was established at the Agua 

 Caliente Ranch, about 18 miles east of Tucson. This ranch is located 

 in the foothills of the Santa Catalina Mountains, near the eastern 

 end of the range, at about 2,800 feet elevation. The various breeding 

 experiments described were conducted in this tent while the field 

 tests were located on the near-by irrigated land. These studies were 

 continued from April 16, 1914, to November 16, 1914. 



DISTRIBUTION OF THE THURBERIA PLANT AND WEEVIL. 



The weevil is not known to occur on any plant other than Thurberia 

 in Arizona, and it seems so closely linked with this plant that every 

 Thurberia plant may be considered as a potential host for the species 

 even though all of these plants do not harbor weevils now. Conse 

 quently knowledge of the distribution of the plant is of great impor- 

 tance in the study of the weevil. 



The distribution of the Thurberia pi\ant is but imperfectly known 

 at present. Explorations have been made in Arizona by Mr. Vernon 

 Bailey, Prof. J. J. Thornber, Mr. O. F. Cook, Dr. A. W. Morrill, Mr. 



1 Coad, B. R., and Pierce, W. D . Studies of the Arizona Thurberia weevil on cotton in Texas. In Proc. 

 Ent. Soc. Wash., v. 16, no. 1, p. 23-27, Mar., 1914. 



Coad, B. R. Recent studies ofthe Mexican Cotton Boll Weevil. IT. S. Dept.Agr.,Bul.231,34p.,Aug.2, 

 1915. 



2 Coad, B . R . Relation of the Arizona Wild Cotton Weevil to Cotton Planting in the Arid West. U. S. 

 Dept. Agr., Bui. 233, 12 p., 4 pi., May 27, 1915. 



