66 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 

 Closely related genera include the following : 



Species Hosts 



Under bark scales or in cracks on trunk and limbs of hosts: 

 Pityococcus ferrisi 



McKenzie Sugar, western white, limber, and pinyon pine. 



California, Arizona, New Mexico, Texas, and 

 Utah. 

 rug ulos us McKenzie .... Pinyon. Arizona. 

 In cells deep beneath bark of branches and trunk of host tree: 

 Desmococeus captivus 



McKenzie Singieleaf pinyon. California. 



sedentarius McKenzie . . Pinyon and singieleaf pinyon. Arizona. 



Other common scales infesting western coniferous trees include 

 the following : 



Species Hosts 



Cryptaspidiotus shastae 



(Cole) Giant sequoia, redwood, and cypress in Cali- 

 fornia. 

 Diaspidiotus ehrhomi (Cole) Douglas-fir and cypress in California. 



Diaspis carueli Targ Cypress, California incense cedar, Port Orford 



cedar, and juniper. Throughout the United 

 States and southern Canada. 

 Ehrhomia cupressi Ehrh. ! 



(68) Monterey cypress and California incense cedar 



in California. 

 Physokermes insignicola 



Craw Monterey pine. 



Toumeyella pinicola Ferris 



(fig. 28) Monterey pine and other pines in California. 



Xylococculus macrocarpae 



(Cole) Monterey cypress and California incense cedar. 



Some of the mealy-bugs also attack forest trees. These are small, 

 soft-bodied bugs covered with a white powdery wax. They are rep- 

 resented by Pseudococcus ryani Coq. on cypress, California incense 

 cedar, and redwood, and P. sequoiae Cole on redwood. 



Species of scale attacking various broadleaved trees (53) are 

 so numerous and most are of so little importance to forestry that 

 they need not be mentioned here. The oystershell scale (Lepido- 

 saphes ulmi (L.)) (45) is an exception, because it proved to be 

 exceedingly destructive throughout the United States to a large 

 number of broadleaved trees and in the West particularly to aspen, 

 cottonwood, poplar, and willow. The mature scales are light to 

 dark brown in color and shaped like a small elongated oyster. 

 They tend to form solid crusts on twigs and limbs and often kill 

 the entire tree. There is one generation annually, with young 

 appearing in May and June. Crude-oil emulsions applied during 

 the dormant season or a light summer oil and nicotine applied 

 just after the young begin to crawl are most effective. 



SPITTLEBUGS 



Spittlebugs, of the family Cercopidae (-47), sometimes do con- 

 siderable injury to forest trees by sucking the juices from leaves 

 and stems. They are called spittlebugs because of the mass of 

 froth, resembling spittle, which covers odd-looking hopperlike in- 



