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



were found in all types of situations at altitudes from about 2,750 

 feet to 7,000 feet, they were more abundant on plants growing at 

 elevations of from 3,500 to 5,000 feet. The writer has been unable 

 to determine any type of location as being especially favorable to 

 the maintenance of the weevils. 



In the Santa Rita Range the writer confined his studies almost 

 entirely to points of less than 4,000 feet elevation. The country 

 examined was that which lies along the base of the mountains com- 

 mencing at a point below Madero Canyon and extending nearly to 

 the northern end of the Santa Rita Range. Throughout most of this 

 country the Thurberia plant was found extending down the arroyo 

 nearly to the 3,000-foot level, and weevils were located on many of 

 these plants at this elevation. 



Very little exploring was done in the Tanque Verde Mountains, 

 but a few trips were made on the northwestern slope above the 

 village of Tanque Verde, where a few plants, some bearing weevils, 

 were located in the "washes" of this comparatively regular slope. 



In the Rincons the investigation was limited to the examination 

 from the southern end of the range of some of the lower arroyos which 

 form the headwaters of the Pantano, and Thurberia plants and a few 

 weevils were found. Messrs. Barber and Schwarz found plants and 

 weevils on the Manning trail above Mills ranch and Prof. Thornber 

 reported a colony from a short distance above the Shaw ranch. 



Investigation seems to have established that the Thurberia plant 

 does not occur in the Tucson Range, as this range was explored by 

 Dr. A. W. Morrill and Mr. W. Dwight Pierce during the summer of 

 1913 with negative results, and a search made by the writer in Sep- 

 tember, 1914, also proved negative. This range seems far too dry 

 for the existence of the Thurberia plant. 



SEASONAL ACTIVITY OF PLANT AND WEEVIL IN NATURE. 



As the activity of the Arizona wild-cotton weevil in nature is 

 largely dependent upon the growing and fruiting period of the plant, 

 close observations were made, particularly in relation to the time of 

 fruiting. These observations showed the time to vary greatly with 

 the location of the plant, and the most important factor seems to be 

 altitude and its accompanying conditions. The plants observed 

 closely during this season ranged from 2,700 to 5,000 feet, and while 

 no definite lines can be drawn, the following discussion gives the 

 variations in time as they were noted at the different elevations. 



Plants growing in the channels of Milagroso, Agua Caliente, and 

 Soldiers Canyon and in the arroyos below these canyons (elevation 

 below 3,000 feet) were all leafed out and squaring heavily by the 

 1st of May. They began blooming about May 7. After two or 

 three weeks of flowering the buds ceased to appear and there was a 



