THE HOP APHIS IN THE PACIFIC REGION. 
(PJiorodon Jiumuli Schrank.) 
INTRODUCTION. 
The hop aphis (PJiorodon Jiumuli Schrank) was known as a pest in 
the hop gardens of England and of Continental Europe long before 
hop growing became an industry in America. In the United States 
this aphis first appeared in New York in 1863, in Michigan in 1866, 
and in Wisconsin in 1867, and in these States it seriously injured that 
crop during the early eighties. It soon reached the Pacific Coast, 
where it first appeared in 1890, and it is now troublesome in most of 
the hop-growing sections of British Columbia, Washington, Oregon, 
and California. 
The investigation upon which this paper is based began during the 
spring of 1911 and was continued through two seasons, being com- 
pleted in the fall of 1912. Experiments were conducted and practical 
control work was carried on at Sacramento and Santa Rosa, Cal., 
and at Independence, Oreg. The recorded efficiency of the various 
insecticides tested is based upon actual counts of living aphides, 
made before and after spraying. The data upon the cost of control 
work and methods employed in field operations are based upon the 
work at Santa Rosa, Cal., and Independence, Oreg., where the prime 
object of this investigation was carried out, i. e., the economical 
control of the aphis of the hop. 
Acknowledgments are due to Dr. F. H. Chittenden, in charge of 
Truck Crop and Stored Product Insect Investigations; to Mr. J. 
Williamson, of Santa Rosa, Cal., who generously assisted me in some 
of the experimental work; to Mr. Theo. Eder, superintendent of the 
E. Clemens Horst Co., who furnished me with a field laboratory and 
a temporary assistant during the summer; to Mr. R. S. Raven, who 
ably assisted me in the life-history and experimental work, and to 
Mr. H. N. Ord, who collected much of the data upon methods and 
cost of control and who carried out the field work in Oregon. 
ECONOMIC IMPORTANCE. 
The hop aphis has probably been present on the Pacific coast 
since the time hops have been grown there on a large scale. The 
greatest injuries from this pest occur in Oregon, Washington, and 
British Columbia, but serious losses are occasionally sustained in 
California. 
74956°— Bull. 111—13 2 9 
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