2 MISCELLANEOUS STUDIES 



PAGE 



Appendix 1. Keys to the genera and tribes of Aphididae; a translation from 



P. Van der Goot _ 154 



Appendix 2. Host plant list _ 159 



Addenda - . 178 



Explanation of plates _ 180 



Index to genera and species 215 



INTRODUCTION 



In recent years considerable attention has been paid to the 

 Aphididae in the United States, and in Europe as well, and a large 

 amount of literature is the result. In California, W. T. Clarke was the 

 first to make any systematic studies of these insects and his paper, 

 published in 1903, embodies the results of these studies. He listed 

 forty-three species, ten of which were described as new. Two or 

 three of his new species are known at present, but the remainder are 

 unknown. Unfortunately his collection was destroyed in the earth- 

 quake of April, 1906, so now it is practically impossible to determine 

 his new species with any degree of accuracy. Following this, there 

 was a period of six years in which there were no publications con- 

 cerning the Aphididae of California, except some economic bulletins 

 from the Experiment Station. In 1909, both E. 0. Essig and W. M. 

 Davidson published the results of their earlier studies. Since then 

 both have added papers occasionally. During 1912 and shortly before, 

 Harold Morrison made an extensive study of the species in the vicinity 

 of Stanford University. He has kindly placed a report of his studies 

 in the author's hands, with permission to publish the records in this 

 paper. The author has been studying the Californian species con- 

 tinuously since 1914. 



At present there are about one hundred and eighty species known 

 to occur in California. This number will undoubtedly be greatly 

 increased as further studies are made, since to date only a compara- 

 tively small part of the state has been covered by collectors. Very 

 extensive collections have been made in Ventura County and in the 

 vicinity of Pomona College, Los Angeles County, by Essig. The San 

 Francisco Bay region, particularly in the vicinity of the University 

 of California and Stanford University, has been carefully surveyed 

 for aphids, collections having been made by Clarke, Davidson, Essig, 

 Morrison, Ferris, and the author. Davidson, Clarke, and Essig have 

 made a few observations in the Sacramento Valley, particularly in 

 Placer and Sacramento counties. The author made a number of 



