UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 903 



»■*> - - -. - i 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



SLW^WU 



Washington,D.C. 



PROFESSIONAL PAPER 



April 22, 1921 



THE GRAPE PHYLLOXERA 1 IN CALIFORNIA, 



By W. M. Davidson, Scientific Assistant, and R. L. Nougaret, 2 Entomological 

 Assistant, Deciduous Fruit Insect Investigations. 



CONTENTS. 



Page. 



California history 1 



Accidental and natural spread 7 



Distribution of phylloxera in Cali- 

 fornia 11 



Vineyard destruction 15 



Nomenclature and synonymy of the 



grape phylloxera 26 



Biology of the grape phylloxera in 



California : 27 



The radicicole 44 



Page. 



The nymph and winged form 73 



Nymphicals or intermediate forms. _ 82 



The sexual forms 90 



The gallicole and its relation to Cali- 

 fornia conditions 95 



Effects of water and heat on phyl- 

 loxera 98 



Diffusion of phylloxera 100 



Summary 122 



Literature cited 127 



CALIFORNIA HISTORY. 



EARLY VINE PLANTING IN CALIFORNIA. 



The grape phylloxera is not native to California. It has long 

 been recognized as originating in North America, but its native 

 habitat is east of the Rocky Mountains. The insect has not established 

 itself upon the native vine of California (Vitis calif ornica) in the 

 wild state, whereas in Arizona it is established on native vines. 



1 Phylloxera vitifoliae (Fitch). 



2 Now in charge, Viticulture Service, California Department of Agriculture, Sacramento, 

 Calif. 



Note. — In connection with other work in California, the office of Deciduous Fruit 

 Insect Investigations, Bureau of Entomology, in cooperation with the Bureau of Plant 

 Industry, has been engaged in an investigation of the grape phylloxera during several 

 years past, with principal headquarters for the work at Walnut Creek. The work 

 inaugurated by E. L. Jenne, upon his death was taken over by S. W. Foster, assisted by 

 R. L. Nougaret. Upon Mr. Foster's leaving the service, the investigation was continued 

 by Messrs. Nougaret and Davidson, the latter giving especial attention to biological and 

 life-history studies and the former to investigations in the field and to remedial opera- 

 tions. The present report deals with the history, injuries, and life history of the insect 

 in California. Remedial measures will be made the subject of another publication. It 

 has been necessary to omit an extended bibliography of the subject. — A.. L. Quaintancb, 

 Entomologist in Charge of Deciduous Fruit Insect Investigations. 

 1900° — 21 1 



