Vol.1] 



Essig. — Aphididae of California 



328 



eanoe birch, B. papyrifera Marsh. The species is abundant 

 throughout the year and causes much smutting of the trees. 



Eucallipterus fiavus Davidson. A pale green species of large 

 size taken in few numbers on the old leaves and in abundance on 

 the tender shoots of the white alder, Alnus rhomhifolia Nutt., 

 in Wildcat Caiion, near Berkeley, California, May 10, 1916. 



Eucallipterus tiliae (Linn.). A beautiful yellow and black 



Fig. 13. My::ocaUis castaneae (Fitch). On leaf of a chestnut tree, 

 Campus, Oct. 10, 1916. (Original.) 



species with black clouded wings which often becomes very 

 abundant on linden trees, producing quantities of honey-dew 

 and giving the trees a black and offensive appearance. Speci- 

 mens were taken on the American linden, Tilia americana Linn., 

 in Golden Gate Park, San Francisco, California, May 25, 1916, 

 and on white or silver linden, T. tomentosa Moench. Berkeley, 

 California, June 17, 1916. 



Myzocallis castaneae (Fitch) (fig. 13). A small yellow aphid 

 which has been called this species occurs on hickory and chest- 

 nut on the campus and is often in large enough numbers to 



