194 INTERNATIONAL CONGRESS OF VITICULTURE 



air and sunlight thus destroying them. This practice will not kill all the 

 pupae owing to the fact that some of the grubs will form cells too low for 

 cultivation to reach them. Again all grubs do not form cells at the same 

 time and thus, if disturbed before the cells are formed, will crawl into the 

 soil and form cells lower than the tools penetrate. 



Destruction of the Adults. The several entomologists, who have experi- 

 mented on the control of this species, have used some form of poison as the 

 most effective method of killing the adults, and this is the method of control 

 that is generally recommended. 



The most extensively used material is arsenate of lead (6 Ibs.) and 

 Bordeaux mixture (8-8-100) 100 gallons. It should be applied as soon as the 

 first beetles appear, using not less than 100 gallons per acre. Where the 

 foliage is dense it will require 150 gallons to cover an acre of grapes properly. 

 A second spraying should be applied in ten days or two weeks. The material 

 just mentioned is most valuable in a vineyard where the foliage is not very 

 luxuriant or where the beetles are not too numerous. In vineyards having 

 excessive numbers of these insects, especially where the foliage is dense, 

 better results are secured by using a spray consisting of arsenate of lead 

 (6 Ibs.), cheap molasses (1 gal.), and water (100 gal.), followed in one week 

 by a single spraying of Bordeaux mixture and arsenate of lead in the pro- 

 portions mentioned above. 



The use of the sweetened spray by the writer was brought about through 

 the apparent failure of grape growers to combat the root-worm by means of 

 the Bordeaux mixture arsenate of lead spray. All workers have found that 

 there is considerable variation, especially some seasons, in the effectiveness 

 of this material. This may have been the result of improper application of 

 the material, due to the interference of wind and dense foliage, or it may 

 have been due to manner in which the poison was made. Our experiments 

 have shown that this material is distasteful to the beetles and this has 

 changed our views regarding the effect produced on the insects. It has 

 usually been assumed that the insects are poisoned but we now hold the 

 opinion that it produces a repellent action on them. In no other way can we 

 account for dead beetles being found under vines where molasses and 

 arsenate of lead was used while in the same field the vines sprayed with 

 Bordeaux mixture and arsenate of lead revealed no dead insects yet the vines 

 were cleared of beetles. Cage experiments have shown that this latter 

 material is distasteful while molasses attracts them. 



It seems that too much dependence has been placed upon the idea that a 

 spray to be effective must eradicate the pest in a single season. The cumu- 

 lative effect of Bordeaux mixture and arsenate of lead upon the infestation is 

 marked when spraying is continued regularly for several years. Although 

 this mixture may not give as decided results as the sweetened spray when 

 used for one season only, especially where the beetles are numerous, still its 

 use in the same vineyard over a period of years keeps the number below the 

 danger mark. The writer has seldom found a vineyard in the Chautauqua 

 and Erie grape belt that is seriously infested with chewing insects where 

 two thorough applications of this spray have been properly applied for a 

 period of five years. 



The great drawback to the sweetened spray is its lack of adhesion. If it 

 should happen to be applied shortly before a rain it will be ineffective be 



