CONTROL OF THE HOP APHIS. 23 
A small predaceous bug, TripJileps 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., hi 1887: 
Triphleps insidiosus Say Camptobrochis nebulosus "CM. 
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 the}' 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 Kosa, 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 primes 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 spraj-ed as soon as the 
