CONTROL OF THE HOP APHIS. 23 



A small predaceous bug, Triphleps insidiosus Say, was occasionally 

 observed among the aphides. 



The following insects were observed by Mr. Theo. Pergande attack- 

 ing the hop aphis at Richfield, N. Y., in 1887: 



Triphleps insidiosus Say Camptobrochis nebulosus Uhl. 



Adalia bipunctata L. Anthocoris sp. 



Stethorus punctum Lee. 



Parasites and predaceous insects destroy large numbers of hop 

 aphides, but in no case have they been observed successfully to con- 

 trol an infestation. 



CONTROL OF THE HOP APHIS. 



AXIOMS OF SUCCESSFUL CONTROL. 



In the economic control of the hop aphis, as of other insect pests, 

 there are certain underlying principles which must be adhered to if 

 the work is to be entirely successful. 



(1) All of the machinery to be used must be capable of doing 

 effective work and must be in good working condition prior to the 

 time at which spraying should commence. 



(2) Spraying must commence at the proper time; it must not be 

 put off. 



(3) The material used must be carefully prepared and thoroughly 

 but not wastefully applied. 



These are fundamental principles, and control work will be less 

 effective and more costly if they are not closely adhered to. 



INSECTICIDES USED. 



Several contact insecticides have been used to control the hop 

 aphis. The most extensively used sprays, however, are tobacco 

 decoctions with whale-oil soap and quassia chips with whale-oil soap. 

 In order to obtain exact data upon the effectiveness of these materials 

 upon the hop aphis a series of experiments on a small scale was con- 

 ducted at Santa Rosa, Cal., and notes were' taken from experiments 

 made on a large scale in Oregon. Tag counts were made; i. e., 20 tags 

 were tied to as many leaves, and records of the number of aphides 

 on the leaves before and three days after spraying were made on the 

 tags; the percentage of aphides killed was thus accurately obtained. 



TIME TO BEGIN SPRAYING. 



It is very desirable to spray all plums or prunes that are infested by 

 hop aphides as soon as the infestation is observed, both in the fall and 

 in the spring. This will check the migration and lessen the infestation 

 of the hops. The hops, however, should be sprayed as soon as the 



