Vol.1] 



Essig. — Aphididne of California 



337 



Aphis avenae Fab. A small dark green species abundant on 

 corn, grain and grasses on the campus. Collected March, 1916. 



Aphis hakeri Cowen. A small pale yellow or pinkish and 

 black species taken sparingly on the flower heads and at the 

 bases of the leaves of red clover, TrifoUum pvaiensc Linn., 



Fig. 22. Aphis albipes Oestlund. Apterous females on tlie leaf of snow 

 berry, Sympliuricarpos racemosiis Michx. Cam])us, March 29, 1916. 

 (Original. Photo by Div. Sci. Illust., Univ. Calif.) 



campus, June 29, and July 25, 1916. Not abundant here at any 

 season. 



Aphis hrassicac Linn. (fig. 23). A pale green species covered 

 with whitish pulverulence and feeding in compact colonies on the 

 common cruciferous plants of the state. Especially injurious to 

 cabbage, cauliflower, brussels sprouts, kale, mustard, radish, 

 turnips, etc. Present throughout the year. 



