254 EXPERIMENT STATION RECORD. 



caused no injury to apple foliage; but more or less siiotting of apple leaves 

 occurred when the poison was used singly or in combination with lime-sulphur 

 or glucose. Zinc arsenite alone or with glucose caused severe burning of grape 

 foliage. Laboratory tests suggest that the injury to foliage by zinc arsenite 

 may be due in part to the solubility of the poison in carbonic acid. The con- 

 tradictory results from the use of zinc arsenite on foliage suggest that the 

 poison as manufactured is not a stable or uniform product. Zinc arsenite or 

 lead arsenate with Bordeaux, soap, or glue continued effective for 25 days. 

 Either of the poisons alone or with glucose gi'adually lost its poisonous prop- 

 erties on exposure to weather and by the end of this period had ceased to 

 protect the foliage." 



The hop aphis in the Pacific region (Phorodon humuli), W. B. Paekeb 

 (U. S. Dept. Agr., Bur. Ent. Bui. Ill, pp. J/S, pis. 10, figs. 8).— This report is 

 based upon investigations commenced in the spring of 1911 and continued 

 through the fall of 1012. Experiments were conducted and practical control 

 work carried on at Sacramento and Santa Rosa, Cal., and at Independence, Oreg. 



The greatest injury from this aphid occurs in Oregon, Washington, and 

 British Columbia, but serious losses are occasionally sustained in California. 

 The author's studies of the life cycle show 2 generations to occur on the alter- 

 nate host, the second one being winged. Five and 6 generations occur on the 

 hop. a part of the fifth becoming winged and depositing young upon the alter- 

 nate host, and part being wingless and depositing young (sixth generation) 

 upon the hop, producing the male aphids which fly to and copulate with the 

 young deposited on the alternate host by the winged individuals of the fifth 

 generation. These fertilized females deposit the winter eggs, which, hatching 

 in the following spring, produce the viviparous insects for that season. 



The winter egg is deposited upon the plum, prune, and hop in the Pacific 

 Coast States. Observations of the winged migrants at Independence, Oreg., 

 have also shown that they occur upon cherry, alder, peach, and apple, and that 

 they deposit their young upon these plants. The author's observations indicate 

 that the aphids emerge from the egg as early as April 10. Only 2 generations 

 were found on the prune; the second is winged and migrates to the hops during 

 the sijring and early summer. In the fall the winged form that produces the 

 sexual female migrates from the hop to its winter host (plum, prune, hop) 

 and later the winged male migrates to the plant on which the sexual female 

 awaits fertilization. The young deposited by the winged aphids are wingless 

 parthenogenic insects, which in from 8 to 12 days grow very rapidly and 

 molt 4 times, immediately after the fourth molt commencing to deposit their 

 young. The number of young deposited by one stem mother was found to be 

 from 29 to 92, with an average of 64 for the 12 aphids under observation. 

 The length of life of the aphids varied from 25 to 3S days, with an average 

 of 30.75 days. The nymphs of the fall migrants became winged in the breeding 

 cages at Perkins, Cal., on August 26 and in the flelcl August 28. Migrants were 

 observed upon plum at Independence, Oreg., September 22, 1912. Young were 

 being deposited there, and upon the next visit to the locality, October 16, many 

 eggs were also present. 



Several predaceous insects are mentioned as enemies. The aphid is readily 

 destroyed by several contact insecticides. It is pointed out that several appli- 

 cations may be necessary to control an infestation successfully. If successful 

 control is desired the spraying operations must not be delayed and the work 

 must be very thorough ; all of the leaves of the vines should be wetted on both 

 sides. Severe infestations have been successfully checked and clean hops ob- 

 tained where the spraying operations were thorough, 



A bibliography of 34 titles is appended. 



