DISCUSSION OF GENERA AND SPECIES 



Genus ICERYA Sign. 

 Icerya purchasi Maskell. 



It will be remembered that this species was originally introduced into 

 the United States at a point in this area. At the present time it occurs 

 rather commonly here, being somewhat of a pest on the pears in the 

 Santa Clara Valley and occasionally killing ornamentals. It has estab- 

 lished itself on certain wild plants, especially favoring mistletoe, but also 

 occurring on sage brush (Artemisia calif ornica) and chamiso (Adenos- 

 toma fasciculatum). 



Genus XYLOCOCCUS Loew. 

 Xylococcus quercus Ehrh. 



1917. Xylococcus quercus Ehrh.; Florence, Ann. Ent. Soc. Am., 10:155-8; figs. 

 1919. Xylococcus quercus Ehrh.; Ferris, Can. Ent., 51:110. 



Originally described from Quercus chrysolepis, Stevens Creek Can- 

 yon, near Mountain View, in this area. I have taken what is probably the 

 same species from Quercus calif ornicus in the hills above Searsville Lake. 

 The species appears to be rather rare and very local in occurrence. 



As I have elsewhere pointed out (ref. cited) it is somewhat doubtful 

 that this species is distinct from X. betulce Perg. I have specimens of all 

 the critical stages of both species and find that the two differ only in 

 the number of median, ventral pores in the first larval stage, betultz 

 having five or six of these pores and quercus two. However, in specimens 

 from Quercus caiifornicus there are as many as nine of these pores. 

 Either the specimens from the two species of oaks should be regarded as 

 separate species or both should be referred to betulce. I am inclined to 

 favor the latter view, but the examination of more material is desirable. 



Genus STOMACOCCUS Ferris. 



1917. Ferris, Can. Ent., 49:375. 



This genus was originally based chiefly upon the presence of mouth- 

 parts in the adult female, but this character is not sufficient to distin- 

 guish it, as other genera of this group are now known to possess mouth- 

 parts in the adult female. I append the following recharacterization of 

 the genus. 



