February, '14] 



DAVIDSON: PLANT-LOUSE NOTES 



133 



.87mm.; cornicles, .443mm.; cauda, .130mm.; antemijB, joint III, .26mm.; joint IV, 

 .25mm.; joint V, .236mm.; joint VI, .125mm.; filament, .443mm. 



Collected singly on Artemisia calif or nica Less, at Walnut Creek, 

 Cal., April 8, 1913. Colonies of Macrosiphum frigidce Oestl., were 

 present on the same plants. This latter species is never pulverulent. 



Aphis atriplicis L. 



Stein mother: General color, pale green; body covered with rather sparse white 

 bloom; body, elongate-oval; head, eyes, legs, antennae, cauda and cornicles, black 

 or dark brown. Cornicles slightly 

 exceeding antennal joint V in length, 

 not much widened in the middle, 

 somewhat curved. Cauda, tapering. 



Measurements: Bodj^, length, ^-^^^^^^^^^ 12 



2.42mm.; body, width, 1.10mm.; 

 cornicles, .097mm.; cauda, .136mm.; 

 antennal joint III, .186mm.; joint 

 VI, .077mm.; joint V, .088mm.; 



joint VI, .088mm.; filament, If 4^ J \^ EJ^ 13 



,126mm. " ' 



Described from several spe- 

 cimens collected April 7, 1913, 

 Walnut Creek, Cal., in curled 

 leaves of Chenopodium murale 

 L. and C. alburn L. 



A phis hakeri Gillette. 

 During the fall and winter 

 months I have collected this 

 species in abundance on a 

 large variety of plants, mostly 

 Compositse. It occurs on sun- 

 flowers, artichokes, Gnapha- 

 lium, Senecio, Artemisia, Anthemis and Amsinckia. It seems peculiar 

 that a species inhabiting legumes and pomaceous fruits east of the 

 Sierra Nevada Mountains, should have such a different range of food- 

 plants on the Pacific Coast. I have never found this louse on either 

 pomaceous fruits or clovers in California. Prof. H. F. Wilson^ reports 

 it from both these hosts in Oregon. The summer life history of the 

 louse in California has yet to be fully studied. On German Ivy 

 {Senecio sp.), at least, it seems to exist the year around and the 

 annuals are infested by migrants from it. I am indebted to Messrs. 

 J. J. Davis and H. Morrison for the determination of this species. 



Hyadaphis xylostei Schank. Syn. Hyadaphis conii Davidson. 



Fig. 5, Aphis atriplicis; 11, stem mother; 

 12, antenna; 13, cornicle; 14, cauda, of stem 

 mother. 



1 Biennial Crop Pest and Horticultural Report 1911-1912, Oregon Agricultural 

 CoUege Experiment Station, p. 89. 



