4 FARMERS BULLETIN 848. 



tion of the Bureau of Entomology. A preliminary examination, 

 made under the direction of Dr. L. O. Howard by Mr. C. H. T. 

 Townsend, showed the enormous capacity for damage of the pest. 

 Subsequent events have verified in every way the predictions that 

 were made at that time, when the insect had not attracted any con- 

 siderable amount of attention in the South. Since 1894 the boll wee- 

 vil has extended its range annually from 40 to 160 miles, although 

 in several instances the mnter conditions have been such as to cause 

 a decrease in the infested area. During the first 10 years after its 

 advent into this country the annual rate of spread was 5,640 square 

 miles. From 1901 to 1911 the annual increase in the infested terri- 

 tory averaged 26,880 square miles. In 1916 it reached 71,800 square 

 miles. Of course, the figures given do not refer to the area in cotton. 

 In many parts of the infested territory the area devoted to cotton is 

 much less than 10 per cent of the total area. 



The territory in the United States in which the boll weevil was 

 found to occur at the end of the year 1916 is showm in figure 1. 



Outside of the United States the boll weevil is known throughout 

 the larger portion of Mexico and southward to Guatemala and Costa 

 Rica, It is known to occur also in the eastern half of Cuba. 



A form of the boll weevil with difterent habits is found in the 

 mountains of Arizona. It feeds upon a wild plant related to cotton. 

 It has not been found to attack any of the planted fields in Arizona, 

 but experiments have shown that it readily attacks the cotton plant. 



DAMAGE. 



The damage done by the boll weevil varies greatly from year to 

 year and also in different parts of the infested area. As the rainfall 

 increases the damage becomes greater. In prairie regions, whel-e the 

 insect obtains little protection through the mnter, it never becomes 

 so numerous as in other quarters where favorable conditions for 

 hibernation are found. These facts, together with variations due 

 to winter conditions, make it rather difficult to estimate the exact 

 damage that has been done. Some years ago the writer stated, from 

 the statistics then available, that the weevil caused a reduction of at 

 least 50 per cent of the cotton crop in regions invaded by it, but that 

 after the first few years the farmers generally resorted to proper 

 means greatly to reduce this loss. Such an mitial fallmg off in pro- 

 duction was confirmed by Prof. E. D. Sanderson, formerly State ento- 

 mologist of Texas, who arrived at his figures in an entirely different 

 way. In many individual cases the means of control recommended 

 by the Bureau of Entomology and demonstrated by the States Rela- 

 tions Service have been applied so successfully that the crop has 

 been fully as large as before the coming of the weevil. 



