NOTES ON SOME APHIDID.E TAKEN IN 

 PLACER COUNTY 



BY W. M. DAVIDSON 



During the month of August, 1910, I was at Penryn, in western Placer 

 County, and was able to spend some time in observing and collecting plant 

 lice in that region. Penryn is in the heart of the Placer County deciduous 

 fruit district, but curiously enough I was unable to find any aphids on fruit 

 trees, although there was abundant evidence — especially on plums and apples 

 — of their presence earlier in the year. I suspect Aphis pomi De Geer, and 

 Hyaloptenis arundinis Fabr. were abundant in the spring. Several fruit 

 growers affirmed that they had been numerous about leafing time. Doubtless 

 Syrphus larvae — I observed a strong Syrphid fauna — and ladybird beetles had 

 done their work. The flora of this region is that of the Sierra foothills. 

 Among the trees most commonly met with are Pimis Sabiniana Dougl., Querctis 

 lohata Nee, Qioercus zinslizenii A. DC. Popuhis fremontii Wats., several species 

 of Salix, and Alniis rhombifoUa Nutt. 



Schizoneura querci Fitch 

 A wooly Schizoneura on both leaves and twigs of Qucrcus wisliccnii A. DC, 

 the valley live calk. The species is abundant and is evidently the same as 

 that found on Quercns agrifolia in the Santa Clara Valley. The specimens 

 agree fairly well with Fitch's species, but this may be a different species. 



Lachnus dentatus Le Baron 

 1 found this insect on the narrow-leaved willow (Salix fluviatilis Nutt.). 

 It is not common. 



Lachnus pini-radiatae Davidson 

 This is a scarce .species and occurs on the needles of Finns Sabiniana Dougl. 



Pemphigus populimonilis Riley 

 This and the next species were observed in abundance on Popuhis fremontii 

 Wats. 



Pemphigus populitransversus Riley 

 .A late and apterous form in the galls. 



Chaitophorus viminalis Moncll 

 Abundant on .S"cr/u- spp. 1 saw some trees whicii were blackened all over 

 by fungi feeding on the honey-dew exuded by this insect. 



Chaitophorus nigrae Oestl(?) 

 This is the same species that occurs in Santa Clara County, and which 1 

 listed as doubtful under Oestlund's species in the Journal of Economic Entom- 

 ology, .'\ug. 1910. I found no winged specimens. The apterous female 



