BECENT STUDIES OF THE MEXICAN COTTON BOLL WEEVIL. 6 



it will be seen that there are three apparent lines of distribution of the 

 species, with Costa Rica as the apex. One line of distribution is along 

 the Pacific slope, and although, according to present knowledge, the 

 Arizona infestation is isolated from that of Sinaloa, Mexico, it is prob- 

 able that the weevil occurs on Thurberia ihespesioides in the moun- 

 tains between these points. The Thurberia plant is known from 

 Chihuahua and Guadalajara, Mexico, which latter locality is within a 

 few miles of weevil-infested cotton. 



The dispersion following the middle line is historic. Since 1880 

 this movement has been watched more or less thoroughly from 

 Tamaulipas, Nueva Leon, and Coahuila, Mexico, until now (1914) 

 it has reached the Georgia line (fig. 1 ) . 



The third line of distribution from Mexico through Yucatan to 

 central Cuba is the cause of considerable speculation as to whether 

 Cuba or the continent was the original source. There is also some 

 speculation as to whether the Central American infestation furnished 

 the nucleus for the dispersion or whether the weevil originated in 

 southern Mexico and dispersed southward. 



FOOD PLANTS. 



The plant longest known as the food plant of the boll weevil is 

 cotton, of which several species are now recorded as hosts — Gossy- 

 pium hirsutum, G. herbaceum, G. barbadense, G. brasiliense, and also 

 several Mexican species. 



Mr. Cook's announcement added as a native food plant the so- 

 called Arizona wild cotton, Thurberia ihespesioides, which grows in a 

 number of mountain ranges in southeastern Arizona, and also in 

 parts of Mexico and probably New Mexico. 



During the summer of 1913, following the discovery of a boll weevil 

 feeding on cultivated Hibiscus syriacus at Victoria, Tex., the writer 

 succeeded in rearing the species on buds of this plant, fed them for 

 some time, and noted the partially complete development in buds 

 of Callirrhoe involucrata and C. pedata, and kept them alive on Sphse- 

 ralcea lindheimeri buds for a short period. 



In the above series of experiments, by alternating foods it was 

 found that the weevils have a wide range of hitherto unsuspected 

 adaptability. This discovery makes the presence of malvaceous 

 plants in the vicinity of cotton a possibly important factor in the 

 ultimate control of the species. The greatest importance of this fact 

 would arise in any attempted cessation of cotton planting as a control 

 measure against the species. 



CHOICE OF FOOD PLANT. 



Two male and two female boll weevils reared from Thurberia buds 

 imported from Arizona were placed with Thurberia buds and with 

 cotton squares to test their food preference. They began feeding 



