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JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 7 



Cauda, .0316mm.; antemise, joint III, .512mm.; joint IV, .297mm.; joint V. .2o5mm.; 

 joint VI, .143mm.; filament, .145mm. 



Described from four specimens collected October 25, 1912. Oak- 

 land, Cal., on Q. rohur L. 



I include this plant louse in this article in the hope that some aphi- 

 dist can help me in the determination of the species. I can not identify 

 it with any American louse and conclude that the species is European 

 as it occurs only on oaks imported from Europe. The aphid seems 

 to approach Myzocallis quercus Kalt. and I have listed it under this 

 name in former papers (Journal Econ. Ent. August, '09 and August, 

 '10). Also it is not this species, but another, that infests the native 

 oaks. 



Monellia caryella Fitch. Infests the under side of the leaves and 

 the nuts of Juglans californica Watson. Collected at San Jose and 

 Walnut Creek, Cal. Kindly determined by Prof. H. F. Wilson. 



Aphis hougtonensis Throop. What seems to be this species in- 

 fests and curls the terminal leaves of wild currant (Rihes sanguineum 

 Pursh.) in the canyons of the hills of Contra Costa Co., Cal. 



Aphis frigidoe Oestl. 



Stem mother: Black or very dark green, covered with fine white bloom and short 

 capitate hairs or spines. Antennae black, reaching to base of cauda; joints II and III 

 (except apex) yellowish-brown; eyes, black; first antenna! joint somewhat gibbous; 



Fig. 4, Aphis frigidoe; stem mother (unshaded). 



prothorax, with small blimt lateral tubercles; legs, black; anterior femora, yellowish- 

 brown; cornicles, black, nearly four times as long as the cauda, their apices conspicu- 

 ously flaring; cauda, dark green, ensiform. The young individuals are pale green 

 with white pulverulence. Measurements: Body, length, 1.57mm.; body, width, 



