BUREAU OF ENTOMOLOGY. 505 



are eliminated by certain rotations of crops. In this way tobacco or 

 corn, whicli is also attacked by the same insect, has been freed from 

 injury. Thus a practical system of avoiding serious damage has 

 been perfected. 



Other tobacco insects have received incidental attention. 



SUGAB-CANE INSECT INVESTIGATIONS. 



The work on sugar-cane insects was interrupted temporarily by the 

 resignation of the agent in charge, who left the service August 31, 

 1910, but has been continued in a satisfactory manner by his suc- 

 cessor. The investigations have dealt with the means of control of 

 the sugar-cane borer, the sugax-cane beetle, and the mealy bug, and 

 have also included special study of the treatment of seed cane to 

 prevent the infestation of new localities by serious pests. All of this 

 work has been done in cooperation with the Louisiana Sugar Ex- 

 periment Station. 



As the sugar-cane borer is by far the most important enemy of 

 the crop in this country, the work was largely concentrated on this 

 species. Extended investigation was made during the fall of 1910 

 of the different classes of injury which this insect inflicts upon sugar 

 cane, and the results have been published. Observations were also 

 made and a considerable amount of valuable information was gained 

 regarding the hibernation and spring emergence of the cane borer, 

 the results of thorough cleaning up of the cane fields in the fall, and 

 other methods of control. An interesting experiment was carried 

 on to test the effect of surrounding sugar cane with different crops. 

 The crops being used at present are corn and cowpeas. This experi- 

 ment will require two years for completion, and will include results 

 with stubble, fall plant cane, and spring plant cane. During the year 

 it was announced by a member of the bureau force that the larger 

 corn stalk-borer of the Eastern States is a distinct species from the 

 sugar-cane borer in the South. If this distinction holds good in 

 Louisiana, it will entirely upset all recommendations regarding the 

 planting of corn upon cane plantations. The experiments so far car- 

 ried on, however, indicate that the forms in cane and corn in Louisi- 

 ana are identical. An investigation of the egg parasites of the cane 

 borer was also begun. 



The sugar-cane mealy bug appears to be restricted to certain local- 

 ities in Louisiana, but threatens to become generally distributed. 

 A predatory beetle was brought from California in large numbers, 

 which fed for two generations upon mealy bugs, apparently with 

 great success, but later died out. 



The experiments with seed cane included fumigation with hydro- 

 cyanic-acid gas, lime-sulphur dip, and whale-oil soap dip, together 

 with other treatments. The three just mentioned gave the best pre- 

 liminary results. 



BICE INSECT INVESTIGATIONS. 



At the beginning of the fiscal year an agent was stationed at Crow- 

 ley, La., to begin studies and experiments in the control of the more 

 important enemies of rice. The Louisiana Rice Experiment Station 

 cooperated generously by furnishing laboratory facilities and access 

 to a large number of experimental rice plats. The work was devoted 

 principally to the rice weevil, which is the most important enemy of 



