20 BULLETIN 160, U. S. DEPARTMENT OF AGEICULTUEE. 



Any of the arsenicals may be used in the form of a spray to control 

 this beetle. If arsenite of zinc in paste form is to be used, the writer 

 will recommend 3 pounds to 50 gallons of water, in combination 

 where possible with some adhesive, in order that best results may be 

 obtained. In the Southwest the prickly pear serves the purpose best, 

 because better results have been obtained where it was used than 

 with any one of several other adhesives. From an economic stand- 

 point, also, it has first rank as an adhesive and spreader. It has been 

 ascertained that zinc arsenite in the powder form in the proportion 

 of 1 pound to 50 gallons of water in combination with cactus gives 

 a little higher mortality than 3 pounds in the paste form, and a more 

 extensive use of this powdered form is to be recommended, particu- 

 larly in the cactus-growing region or where the glutinous matter of 

 this plant can be had for use in the spray. 



WASHINGTON : GOVERNMENT PRINTING OFFICE : 1915 



