APHIDID.E OF SOUTHERN CALIFORNIA VIII 



E. O. ESSIG 



SECRETARY OF STATE HORTICULTURAL COMMISSION 



SACRAMENTO, CALIFORNIA 



Southern Californi.i with its varied flora and mild climate affords an ex- 

 cellent place for the collecting and studying of Plant Lice (A))hidid«). At first 

 the field seemed unfavorable, especially was this impressed upon me during the 

 first two years of my work on this family. This is accounted for. in a great 

 measure, by lack of experience in field collecting and in close observation. Then 

 too. tlic first operations were carried on in a much drier region than is usually 

 found nearer the coast. In Ventura County, and particularly in the vicinity of 

 Santa Paula, I have been able to take a great number of new species and even 

 a few new genera, and all of this is practically the work of a single spring and 

 summer. No doubt the same is true throughout a great ])art of the State and 

 especially further south, the entire field being practically new. In fact I know of 

 only one new species being reported south of Los Angeles and that by Prof. 

 Cockerell. who described Aphis fetrapteralis Ckll. taken on Atriplex canescens 

 tetraptera at La Jolla. (Bull. So. Calif. Acad. Sci., I, No. t, April 1, 1902). 

 From some ten species received from Imperial County this summer, only four 

 were known to me, but the material received was in such poor condition that a 

 careful study could not be made, so as to warrant descriptions of new species. 



As stated, further on, several of the new species and two of the genera are 

 close links between other species and genera already described. 



I wish to acknowledge, here, the special and most valuable aid of my brothers, 

 S. H. Essig and F. M. Essig, in collecting and in discovering many of these 

 most interesting forms. 



PEMPHIGUS Hartig. 



Type Aphis bursarius Linn. 



Ke_v to California Species 



1. Not a gall- forming spcies; subterranean, or partially so, in habits. 2 

 Forming galls, pseudogalls, or curling the leaves; distinctly aerial in habits. 3 



2. Transverse sensoria only on antcnnal articles III and IV. distinctly 



subterranean. hctae 



Transverse sensoria on articles III, IV and V; only parti.illy subter- 

 ranean in habits. califoniiciis 

 'J. Forming distinct galls. "l 

 Forming pseudogalls or simply curling the leaves. 6 

 ■t. Forming large, singular galls on the petioles near the bases of the 



leaves ; large numbers in each gall. 5 



Forming many moniliform galls on the surfaces of tiie leaves, a single 



individual in each gall. popullmonilis 



5. Galls globular in form, antenna' rough with transverse sensoria on 



antcnnal articles III, IV, V and VI. populicaulis 



