A SYNOPSIS OF THE APHID1DAE 33 



Genus Chaitophorus Koch 



Koch, Die Pflanzenlause, p. 1, 1854. Type Aphis aceris Linn. 



There are at present no species of this genus in California; most 

 of the species hitherto placed in it are now considered as belonging 

 to the genus Thomasia Wilson. 



12. Genus Arctaphis Walker 

 Walker, The Zoologist, p. 2000, 1870. Type aphis populi Linn. 



This genus as defined by Wilson is represented in California by 

 two species: A. viminalis (Monell) and A. populifolii (Essig). The 

 latter was placed by Essig in a new genus, Eichochaitophorus, but 

 there is not enough difference between these to warrant a new genus. 



KEY TO CALIFORNIA SPECIES 



1. Wings hyaline. Three-nine large sensoria on third antennal segment (fig. 71). 



IV half as long against as V populifolii (Essig) 



Wings subhyaline. About ten rather small sensoria on III. IV but very 

 little longer than V viminalis (Monell) 



28. Arctaphis populifolii (Essig) 



Figures 69, 71 



Essig, Pom. Jour. Ent., vol. 4, p. 722, 1912. Eichochaitophorus (orig. 



desc.). 



Davidson, Jour. Econ. Ent., vol. 3, p. 375, 1910. Chaitophorus populifoliae 

 (Fitch) (desc. male). 

 Davidson, Pom. Jour. Ent., vol. 3, p. 399, 1911. Chaitophorus populifoliae 



(Fitch) (list). 



Records. Populus trichocarpa, Santa Paula (Essig), Berkeley, September, 

 1915; Populus fremontii, Stanford University and Penryn, Placer County (David- 

 son) ; Menlo Park, San Mateo County, October, 1914 (Morrison) ; Berkeley, Sep- 

 tember, 1915; El Cajon, San Diego County, June, 1916; Kiverside, October, 1916. 



In 1912 Essig described this species from specimens taken on 

 Populus trichocarpa at Santa Paula, and placed it in a new genus, 

 Eichochaitophorus. He separated this genus from Arctaphis for the 

 following reasons : 



According to Wilson the cauda [in Arctaphis] is a knob on a quadrangular 

 base. The anal plate is broadly rounded. In the new genus [Eichochaitophorus] 

 the style has a distinct neck and is situated on a very distinct conical base. The 

 anal plate is deeply notched in the middle so as to make it somewhat forked as 

 in the genus Callipterus. 



