ARIZONA WILD COTTON WEEVIL. 6 



DISTRIBUTION. 



The discovery that the weevil breeds on Thurberia furnished the 

 first intimation that it lives on any plant other than those of the 

 genus Gossypium, though the writer has since demonstrated that it 

 is able to develop on some other closely related malvaceous plants. 

 However, it is not likely that this occurs in nature under normal con- 

 ditions, and there is no reason for believing that the weevil feeds 

 upon any plant other than Thurberia in the mountains. Conse- 

 quently a study of the distribution and habitat of Thurberia is second 

 in importance only to that of the weevil itself. While our knowledge 

 of this point is by no means complete, considerable information has 

 been gathered in the course of a number of explorational expeditions, 

 and we possess a fair general idea of the conditions. 



In Arizona Thurberia is known to occur in the Santa Catalina, 

 Santa Rita, Tanque Verde, Rincon, Mule Pass, Huachuca, Chiricahua, 

 Superstition, Bradshaw, Dos Cabezos, and Dragoon Mountains; at 

 Globe, and in Fish Creek Canyon of the Salt River Valley. In Mexico 

 it has been recorded from Guadalajara, southwestern Chihuahua, and 

 a number of localities in eastern Sonora. The weevils have been found 

 only in the Santa Catalina, Rincon, Santa Rita, Tanque Verde, and 

 Dos Cabezos Mountains. Of these ranges the first four adjoin the 

 Santa Cruz Valley, in which Tucson is located, and the last is near 

 Bowie. From these data it is seen that the plant is rather generally 

 distributed throughout the southeastern part of Arizona and that the 

 weevil infestation, so far as is known at present, is more or less con- 

 centrated around Tucson. Of course, additional explorational work 

 will undoubtedly disclose new localities where both plant and weevil 

 are present. 



Because of the apparent concentration of the weevils around 

 Tucson it was believed that this was the point of greatest danger of 

 infestation of the cultivated cotton, and the economic investigations 

 were conducted there. While the largest area of cotton cultivation in 

 the State is in the Salt River Valley in the vicinity of Phoenix, the 

 weevil has not been found near there, and the Santa Cruz Valley 

 seemed in more immediate danger. 



THE THURBERIA PLANT. 



Many of the habits of the weevil are directly dependent upon the 

 characteristics of the Thurberia plant, and the habitat and activities 

 of this plant have been carefully observed. It is found at altitudes 

 ranging from a little over 2,000 feet to 7,000 feet. While colonies are 

 frequently found high on the sides of the canyons and on the ridges, 

 the most common habitat in the mountains around Tucson is in the 

 beds of the canyons and small washes. Here it grows among the 



