THE HOP APHIS IN THE PACIFIC REGION. 



(Phorodon Jiumuli Schrank.) 



INTRODUCTION. 



The hop aphis (Phorodon humuli 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 



