52 BOARD OF AGRICULTURE. [Pub. Doc. 



stitute for the arsenical poisons has as yet been found, when 

 all things are taken into consideration. Something only 

 mildly poisonous, such as Bug Death (practically impure 

 zinc oxide, finely ground), will, if liberally applied, free 

 the vines from this pest, but such things are expensive and 

 time consuming in then- application. The arsenical insecti- 

 cides are best, applied with water, in the form of a fine spray, 

 as soon as the slugs appear. To kill all the bugs the poison 

 must be distributed over the entire plant. Unless applied 

 in connection with Bordeaux mixture it is safest to use lime 

 with all arsenical compounds. The applications should be 

 repeated as often as necessary (formulas 3, 3a, 4 and 4«). 

 Some of the cheaper arsenoids are as effective as Paris 

 green. There is no reason for using them or Paragrene in 

 place of Paris green unless they can be had at a lower price. 

 Lead arsenate is the most satisfactory of the insecticides 

 used by the station. It is apparently slower in action than 

 the copper compounds of arsenic, but it can be more evenly 

 applied, and it adheres firmly to the foliage without burn- 

 ing. Early application, as soon as the eggs hatch, is 

 important, because the young, small slugs succumb more 

 readily to arsenical poisons than do the large, nearly full- 

 grown ones. 



The purity of Paris green can be quite readily and fairly 

 accurately tested by dissolving the Paris green in strong- 

 ammonia water. If pure all of the Paris green will dissolve, 

 the solution turning a deep blue color. Undissolved sedi- 

 ment indicates impurities or adulterations. Another test is 

 to place a little of the Paris green between two pieces of 

 window glass and rub them together. If the Paris green 

 is adulterated with lime, barium sulphate, or similar white 

 materials, the Paris green will appear to turn white in 

 places. Paris green of good quality is intensely bright 

 green and uniform. When adulterated, the green loses 

 something of its intensity and is grayish green and is not 

 always uniform. 



Although the purity of the Paris green is of the greatest 

 moment, its mechanical condition is also important. To 

 thoroughly protect the plant it is necessary that the poison 



