504 ANNUAL REPORTS OP DEPARTMENT OF AGRICULTURE. ' 



in view. There are many important practical obstacles to be over- 

 come, but the work done has yielded results sufficiently definite to 

 warrant hope of a successful outcome. 



The study of the j^arasites of the boll weevil was continued, and 

 experiments were made in introducing Texas parasites at two points 

 in Louisiana, namely, Crowley and Livonia. 



The study of the local modifications in the habits and life hisiory 

 of the weevil under the conditions of the Mississippi Delta was 

 continued ; a large number of remedies was tested, and in addition 

 to poisons and repellents of various sorts a number of special ma- 

 chines was investigated. The importance of trying every remedy 

 suggested, in order that definite advice may be given to planters, was 

 indicated during the season by the organization of a large company in 

 Texas for the sale of cotton seed treated by some chemical process 

 which was claimed to have the effect of making the plants immune to 

 wee\"il attack. 



During the season the exact status of the boll weevil throughout 

 the infested territory was determined. This work is necessary in 

 order that the bureau may be ready to furnish information demanded 

 by planters, cotton dealers, and others, and is of especial importance 

 to States that are about to be invaded by the weevil. 



The advance of the boll weevil into new regions was investigated 

 with care. In this work the bureau cooperated with the entomolo- 

 gists of several States, notably Mississippi and Alabama. 



TOBACCO INSECT INVESTIGATIONS. 



The principal work on tobacco insects consisted of (1) investiga- 

 tions of means of control of the so-called hornworms and (2) the 

 investigation of the control of the so-called tobacco wireworm {Gram- 

 hus caliginosellus) . The headquarters for the work on hornworms 

 were at Clarksville, Tenn. ; those for the wireworm investigations at 

 Appomattox, Va. 



The main work on the hornworms was the investigation of control 

 by either chemical or cultural methods. With chemical methods 

 many experiments were tried with arsenate of iron, arsenate of lead, 

 Paris green, and arsenic bisulphid. The latter substance was very 

 effective when applied at the rate of 2 pounds per acre — about as 

 effective as Paris green. It can be applied without the use of a 

 carrier and its bulk per pound is less than that of Paris green. The 

 price should be very low. This substance, however, has a caustic 

 effect upon the tobacco plant, but since the product used in the ex- 

 perimental work was not especially prepared for an insecticide, 

 strong hopes are entertained that the especially washed product on 

 hand for use during the present year may prove to be harmless to the 

 tobacco. Some interesting points were ascertained regarding cul- 

 tural methods of control of the hornworms, but the chemical means 

 of reducing injury will best suit the needs of the planters. 



The work on the tobacco wireworm has progressed in a satisfactory 

 manner. The previous season's studies on the life history and sea- 

 sonal history were verified and enlarged. Many experiments with 

 remedies were conducted. All observations and experiments strength- 

 ened the belief that it is only by cultural means that this pest can be 

 controlled. It feeds naturally upon certain weeds, and these weeds 



