DISCUSSION OF GENERA AND SPECIES 51 



Aspidiotus ehrhorni Coleman. 



Fig. 28. 



Within this area this species has been taken only from the bark of 

 Pseudotsuga taxifolia. 



The original description is in error in the statement that there are 

 three pairs of "incisions" on the pygidium. There are but the usual two 



Fig. 2S.^Aspidiotus ehrhorni Coleman: pygidium of specimen from Pseudotsuga 

 taxifolia on the Santa Cruz Peninsula. 



pairs. I may note further that the derm is membranous, except for the 

 pygidium, and that the tubular ducts are confined to the pygidium, except 

 for one or two at the lateral margins on some of the abdominal segments. 

 The figure accompanying the original description is quite inadequate and 

 I present a new figure. 



Aspidiotus hederae (Vail.). 



Sharing with A. rap ax the distinction of being one of the two 

 most common scales in this area. It occurs on an extremely wide range 

 of wild and cultivated hosts, among the former being Arbutus menziesii, 

 Alnus rhombifolia, several species of Arctostaphylos, Umbellularia cali- 

 fornica, Ceanothus sp. and Sequoia sempervirens. 



Aspidiotus osborni Ckll. 



Fig. 29. 



Quite common on the bark of Quercus agrifolia, but rarely seen be- 

 cause of the close resemblance of the scales to the bark of the host. 



Aspidiotus yulupce Bremner is a synonym of this. I may note that 

 the derm of the abdomen is membranous, except for the pygidium, and 



