A SYNOPSIS OF THE APHIDIDAE 143 



These observations of Maxson's together with those made by the 

 author lead to the conclusion that all the reported cases of infestation 

 of beets and other hosts by P. betae Doane in California do not neces- 

 sarily refer to this species. Never have the fuiidatrix or fundatrigenia 

 been taken on poplar in California. This strengthens the point that 

 the aphids on beets and other hosts may not all be P. betae Doane. 

 Further studies and observations will have to be made before this 

 point can be settled, however. 



165. Pemphigus populicaulis Fitch 



Fitch, Eep. Ins. N. Y., vol. 5, p. 845, 1859 (orig. desc.). 



Clarke, Can. Ent., vol. 35, p. 248, 1903 (list). 



Davidson, Jour Econ. Ent., vol. 2, p. 299, 1909 (list). 



Davidson, Jour. Econ. Ent., vol. 3, p. 372, 1910 (list). 



Davidson, Jour. Econ. Ent., vol. 3, p. 372, 1910. P. populi-transversus Biley 



(list). 

 Davidson, Pom. Jour. Ent., vol. 3, p. 398, 1911. P. populi-transversus Riley 



(list). 



Essig, Pom. Jour. Ent., vol. 4, p. 699, 1912 (list). 

 Essig, Pom. Jour. Ent., vol. 4, p. 708, 1912 (dese.). 

 Davidson, Jour. Econ. Ent., vol. 8, p. 420, 1915 (sexuales). 



Records. Populus fremontii, P. trichocarpa; from Placer County to San Diego 

 County (Clarke, Davidson, Essig, Morrison, and the author). 



The species infests cottonwoods throughout the state, forming a 

 gall by the twisting of the leaf petiole. The sexuales are found, 

 according to Davidson, under the bark where the eggs are also laid. 

 The author has found the species in San Diego County, having taken 

 the fundatrix, virgogenia, and fundatrigenia in galls in May, 1916, 

 and the dead sexupara at the same time in old galls. These latter 

 probably died without ever leaving the galls. 



166. Pemphigus populi-transversus Riley 



Eiley, U. S. Geog. Geol. Surv., Bull. 5, p. 15, 1880 (orig. desc.). 

 Essig, Univ. Calif. Publ. Entom., vol. 1, p. 343, 1917 (list). 



Records. Populus fremontii, Berkeley, September, 1914 (Essig), Eiverside 

 September to October, 1916, May to July, 1917. 



This species forms large galls on the leaf petioles of poplar some- 

 what similar to the preceding species, differing in that the opening is 

 on the opposite side of the gall, and is transverse rather than oblique. 

 Essig 's specimens were determined by Gillette, the author's by Max- 

 son. Davidson reported a species under this name from Stanford 



