VI. COMBATING THE COTTON- WOOD LEAF-BEETLE. 



April 21st, Mr. Joseph Kennedy, a leading willow grower of 

 Liverpool, N. Y., wrote to us that the Cotton-wood Leaf-beetle, 

 or " Willow Beetle," as the insect is more frequently called in 

 that vicinity, had again appeared in great numbers, threatening 

 serious damage to the crop of willows. 



Tor several yeais past this insect has been a very serious pest 

 to growers of basket willows. It has also been complained of as 

 attacking young poplar trees growing in the nursery.* We vis- 

 ited some of the leading growers in the vicinity of Liverpool and 

 found, that although spraying with Paris green had been resorted 

 to, it seemed to have but little effett upon the insects. In two 

 instances we found that the Paris green which had been used 

 was of an inferior quality, being adulterated with lime. In other 

 instances, however, where the poison had been applied with con- 

 siderable care, the effect had been scarcely more encouraging. 



For the purpose of making a more thorough test than had 

 yet come to our knowledge with green arsenite and arsenate of 

 lead as remedies for this insect, a small field of about one acre 

 of willows was secured. The field was divided into three plots. 

 Plot 1 contained about three-fourths of an acre. Plots 2 

 and 3 were of equal size, and included the remainder, with 

 the exception of a few rows which were left unsprayed. Plot 

 1 was made larger than the others, as we wished to use a 

 power sprayer. (A Peppier sprayer, owned by Mr. Kennedy upon 

 whose farm the experiments were made, was used.) Plots 2 

 and 3 were sprayed with a knapsack sprayer. 



Plot 1 was sprayed May 5 and June 19 with green arsenite, 

 one pound of the poison to 1.50 gallons of water being used. In 

 the first application sufficient lime was added to make the mix- 

 ture of a slightly milky color; in the second glucose was added, 

 together with the lime, at the rate of two quarts to 45 gallons, 

 and in the third application the same amount of glue was added 

 in the place of the glucose. 



♦Fourteenth Annual Report New York Agricultural Experiment Station, page 658. 



