10 THE HOP APHIS IN THE PACIFIC REGION. 



In 1911 the hops at Santa Rosa. CaL, were severely attacked by 

 this aphis. In fact, if the hop crop of the world had not been small 

 and the demand for hops consequently very great, many of the 

 growers in this section would have been unable to dispose of their 

 crops. During the same season the financial loss due to injury by 

 this aphis to the crops on two large yards in British Columbia was 

 estimated at S80.000. 



In 1912 the loss due to this insect was particularly severe in Ore- 

 gon. One company which handles about 20,000 bales estimated 

 that 50 per cent of their hops were badly damaged and would sell 

 for 15 cents per pound, while 30 per cent was slightly damaged and 

 would sell between 15 and IS cents per pound. The remaining 20 

 per cent was not injured and would sell for the prevailing price of 

 20 cents. At this rate the loss would aggregate $124,000. The crop 

 on a yard of 110 acres was so severely injured that 20 acres were not 

 worth picking. The loss in this yard was $12,000. 



The damage in these cases was unusually severe, but this pest if 

 not controlled is, under favorable conditions, capable of causing 

 such injury to both the hop vines and the hop cones as to entail a 

 total loss. 



LIFE HISTORY. 

 HIBERNATION. 



The winter egg is deposited by the oviparous female upon the 

 plum, prune, and hop in the Pacific Coast States and upon the sloe, 

 plum, bullace. 1 and probably the hop in England and Continental 

 Europe. 



The first generation and the winged migrants were observed upon 

 French prune at Santa Rosa and Perkins, CaL. during May and 

 June in 1911 and 1912. The migrants which were observed May 29. 

 1912, were upon the ordinary though tender foliage, but those 

 observed later in the season were found only upon some very succu- 

 lent, suckerlike growths. Xo hop aphides were found upon the 

 surrounding older and tougher leaves. This observation was made 

 both in Santa Rosa and Perkins, and it was found that by selecting 

 such growths aphides could almost invariably be found. 



APHIDES OX HOP ROOTS. 



Prof. W. T. Clarke, of the California Experiment Station, stated 

 that while "studying this insect at Watson ville, CaL. during the last 

 of January or first of February. 1904, some hop roots were brought 

 to him on which were many living hop aphides. He stated that 

 there is no doubt about the identification of this insect. The writer 



i Journ. Board Agr. Great Britain, vol. 19, Xo. 4, p. 297, 1912. 





