2 BULLETIN" 233, U. S. DEPARTMENT OF AGRICULTURE. 



Brownsville, Tex., about 1892. Since that time it has advanced 

 steadily northward and eastward until at the present time it is in 

 Texas, Louisiana, Oklahoma, Arkansas, Mississippi, Alabama, and 

 Florida, and the total area infested in 1914 was 312,300 square miles. 

 Estimates made by the Bureau of the Census place the total loss in pro- 

 duction of cotton lint in the United States due to the ravages of this 

 species at 10,000,000 bales, or a money. loss of $500,000,000. Thus 

 we see the importance of this little beetle of insignificant appearance 

 in the area now infested. 



Extended studies have been made by the Department of Agri- 

 culture and also by the various State offices in the attempt to reduce 

 the damage done by the species. It has proven one of the most 

 difficult insects to combat, owing largely to its habit of feeding at 

 all times on inner plant tissue and so making the use of poisons prac- 

 tically worthless. The most effective methods of reducing damage 

 which have been developed are principally cultural. 



During the summer and fall of 1913 the writer experimented with 

 the Arizona wild cotton weevil and the Texas cotton weevil at Vic- 

 toria, Tex., crossbreeding them and testing the adaptation of the 

 Arizona form to conditions of cultivated cotton in the South. In 

 April, 1914, the work was transferred to a ranch near Tucson, Ariz., 

 and was continued until the middle of November. This bulletin is 

 a partial result of these studies. 



Although the Thurberia plant has been studied botanically for 

 some years, owing to its close relation to cotton, economic interest 

 from an entomological standpoint was first aroused early in 1913, 

 when Mr. O. F. Cook, of the Department of Agriculture, announced 

 the discovery of the weevil breeding in the bolls of this plant in 

 Arizona. This announcement was at once followed by a study of 

 the exact taxonomic status of the weevil, its distribution, habits, and 

 probable economic importance. It was soon found to be not identi- 

 cal with the cotton-boll weevil of the South, but so closely related 

 that the two forms would interbreed readily. It was then described 

 as a variety of Anthonomus grandis by Mr. W. Dwight Pierce, of 

 this bureau, and given the varietal name thurberix. Further in- 

 vestigations lead to the belief that the two types are geographical 

 and environmental varieties arising from a common ancestral form 

 which was probably native to some point in southern or central 

 Mexico. The two forms have probably spread northward along sep- 

 arate lines of distribution in the course of time and have acquired 

 slight differences in structure and habit. 



These differences in structure of the adult beetles are so slight that 

 they are not apparent to the untrained eye and the descriptions 

 used in this paper are applicable to either type. 



