A SYNOPSIS OF THE APHIDIDAE 3 



observations in the vicinity of Fresno during May and June, 1915, and 

 more or less extensive observations and collections during 1916 and 

 1917 in San Diego, Riverside, Orange, Los Angeles, and San Bernar- 

 dino counties. In addition to these, reports come to the College of 

 Agriculture occasionally from the State Insectary and the various 

 county horticultural commissioners. A summary of the above state- 

 ments shows that extensive collecting has been done only in the 

 territory adjacent to San Francisco Bay, and throughout southern 

 California. The whole northern half of the state, the great interior 

 valleys of the Sacramento and San Joaquin rivers, and the desert 

 sections of the southeastern part of the state are as yet unexplored. 

 Undoubtedly many interesting species will be found in these parts. 



The author wishes to express his appreciation of the aid rendered 

 by various people during the past three years of study. To Harold 

 Morrison of the Federal Board of Horticulture is due especial thanks 

 for his assistance during the early part of the author's study, for his 

 collection notes, and for the use of his extensive collections of Stanford 

 University vicinity and Indiana; Jo E. 0. Essig of the University of 

 California for his continuous advice and assistance, for the use of 

 his large collections of Californian species, and for the reading of 

 this manuscript; to W. M. Davidson of the Bureau of Entomology, 

 U. S. Department of Agriculture, for his many notes and deter- 

 minations and for the use of his collection; to A. C. Baker, J. J. 

 Davis, C. P. Gillette, A. S. Maxson, E. M. Patch, and H. F. Wilson 

 for their many determinations and suggestions ; to R. W. Doane of 

 Stanford University for the permission to work over his collection 

 of Utah aphids and for permitting his students to use the keys included 

 in this paper, thereby finding the weak points in the keys ; and finally 

 to G. F. Ferris of Stanford University for collections and advice. 



In this paper the author has brought together all the present 

 records of California Aphididae. He has included keys for the 

 determination of the subfamilies, groups, genera, and species, together 

 with such illustrations as are necessary for an understanding of the 

 keys. The discussion of each species includes a bibliography of thf 

 California literature (exclusive of the merely economic and popular), 

 together with a citation of the original description and the best 

 available description, a list of host plants and localities, and a dis- 

 cussion of the synonomy, life history, and habits so far as they are 

 known. The descriptions of certain species are not readily accessible 

 and of others not at all adequate. Such species have been redescribed 



