New York Agricultural Experiment Station. 21 



was so effectual in destroying the canker-worms that another 

 application was not necessary. 



Young cut-leaf birch trees, badly infested with thrips, were 

 sprayed three times with a whale-oil soap in solution, to which 

 was added one ounce of flowers of sulphur to one gallon of the 

 soap solution. This combination proved highly successful, show- 

 ing that this serious pest can be controlled. 



Experiments in fumigating nursery stock with hydrocyanic acid 

 gas. — These experiments are not yet completed, but the indica- 

 tions now are that nursery stook can be successfully fumigated 

 in large frost-proof cellars where the trees are ordinarily stored 

 over winter, without going to the expense of building houses for 

 this purpose where stock can be fumigated in small lots only. 



Spraying experinwnts tvith green arsenitc. — These experiments 

 form a part of a series of experiments with green arsenite begun 

 in 1896, their object being to test the value of green arsenite as 

 compared with Paris green. 



Fourteen large trees owned by O. L. Jackson, at Bushville, 

 were used for the experiments and were sprayed three times. 

 Examinations made soon after the first application showed that 

 only the young worms, those about one-fourth inch long, had 

 been killed by the spray. After the third application the trees 

 were practically free from worms, the older ones having finally 

 succumbed. 



This indicates that green arsenite may be slow in its action but 

 where the trees were sprayed three times it was effectual. 



Investigations and experiments with plant lice. — Four species of 

 plant lice have been under observation during the past season, 

 two infesting the plum and two infesting the currant. The work 

 of studying out the complete life histories of these species is not 

 yet complete. The best progress has been made with Hyalopterus 

 pruni. All stages but one have been observed and drawings 

 made. In all the other species studied, with the probable excep- 

 tion of Myzus, new facts concerning their life histories have been 

 brought to light, and their various forms figured for the first 



