68 THE GKAPE ROOT-WORM. 



In view of the results described above, there can be no doubt as 

 to the value of a poison as a direct and effective killing agent of the 

 beetles in the open field. It is quite possible, moreover, that the 

 rapid removal of dead bodies by ants and other agencies and the 

 close search required to find them on account of the fact that their 

 color is the same as that of the soil, and also by the fact that they 

 were distributed over a large area on the foliage of full-grown vines, 

 have resulted in the failure of other workers to find a sufficient num- 

 ber of dead bodies of beetles in sprayed vineyards to warrant them 

 in feeling that this method of control is as effective as might be 

 desired. 



COMPARATIVE EFFECTIVENESS OF ARSENATE OF LEAD AND 



ARSENITE OF LIME. 



In our field work with arsenical sprays, planned for a period of 

 two or three seasons, arsenate of lead was the insecticide used 

 throughout the experiments. Since, however, many vineyardists 

 were using arsenite of lime when this investigation commenced, it 

 was deemed advisable to make a test of its efficiency as an insecti- 

 cide against the grape root-worm beetle as compared with arsenate 

 of lead. 



In the summer of 1907 a test of these two insecticides was made 

 in two vineyards in different parts of the township of North East. 

 One vineyard of about 8 acres belonging to Mr. W. S. Wheeler was 

 divided into three plats. Two plats of about 3 acres each were 

 sprayed, one with Bordeaux mixture and arsenate of lead and the 

 other with Bordeaux mixture and arsenite of lime. The third plat 

 of about 2 acres running through the middle of the block was left 

 unsprayed. Two spray applications were made on these plats at 

 the same dates, July 9 and July 27, with a gasoline-engine power 

 sprayer (PL X, fig. 2). The spray was applied at a pressure of about 

 100 pounds, and about 100 gallons of the liquid were used per acre. 

 The formula used on the plat sprayed with arsenite of lime was, 

 copper sulphate, 5 pounds; lime, 6 pounds; resin-fishoil soap, 2 

 pounds, and 1 quart arsenite of lime made according to Kedzie's 

 formula (containing 4 ounces of white arsenic) to 50 gallons of water. 

 The resin-fishoil soap was added to increase the mixture's property 

 of adhering to the foliage. The formula used on the plat sprayed 

 with arsenate of lead was, copper sulphate, 5 pounds; lime, 5 pounds; 

 arsenate of lead, 3 pounds; and water, 50 gallons. The effect of these 

 treatments in preventing egg deposition is shown by a count of the 

 egg clusters on 25 vines in each of the three plats. It should be 

 stated in addition that at the time of making the count of egg depo- 

 sition there was evidence of a great deal more feeding by beetles on 

 the foliage on the plat treated with arsenite of lime than upon the 



