INSECT ENEMIES OF WESTERN FORESTS 47 



Species of Cinara Hosts and distribution 



C. schwarzi Wilson Ponderosa and other pines. Arizona and 



Colorado. 



C. pseudotsugac Wilson Douglas fir. Oregon. 



C. taxifoUa Sw Douglas fir. California. 



C. braggi Gill Bine sprnce. Colorado. 



C. caudelU Wilson Spruce. British Columbia. 



C. palmerac Gill Engelmann and other sprnce. Colorado. 



C. picea Panzer Spruce. California. 



C. vandykei Wilson Spruce. Washington. 



C. ferrisi Sw White fir. Northern California. 



C. pacifica Wilson Lowland white fir. Northern California. 



C. occldentalis Davidson White fir. Oregon and California. 



G. hurriUi Wilson Juniper. Colorado and Idaho. 



C. tujdfilinufi DelG Aborvitae, cypress, and cedars. California. 



Speuce Gall, Bark Lice 



Cone-shaped galls which form on the twigs of spruce trees are 

 caused by several species of gall and bark lice belonging to the genera 

 Adelges and Pineus (i) (formerly called Chermes). These galls fre- 

 quently kill the terminals but rarely endanger the life of the trees and 

 are of little importance under forest conditions. On seedlings and 

 saplings in nursery or plantation, and on ornamental trees in gardens 

 and parks, the formation of these galls is of more consequence, since 

 they kill the tips of branches and tend to stunt and deform the trees. 



Most of these insects have an alternate host tree upon which they 

 appear in a different form. On pines and Douglas fir these alternate 

 forms appear as a dirty white w^ax on the bark or as small tufts of 

 cottony wax on the needles. Often these bark lice exude a honey- 

 dew upon which a black smut grows, and accumulations of this make 

 trees very unsightly. 



In nursery and plantation the gall lice can be controlled by cutting 

 and burning the green galls before the insects have emerged in the 

 spring, or by spraying the trees early in the spring, when the young 

 begin to colonize on the new growth. For this purpose use a miscible- 

 oil spray composed of 5 gallons of miscible oil, 1 quart of 40-percent 

 nicotine sulphate, and 200 gallons of water. 



Cooley's gall louse {Adelges cooleyi Gill.) is the species most fre- 

 quently responsible for the formation of cone-shaped galls on ter- 

 minal twigs of blue spruce, Engelmann spruce (fig. 21), and Sitka 

 spruce in the West. Two or more other species do similar damage. 

 The galls are from 1 to 2 inches in length, light green to dark purple, 

 and are formed by the growling together of the basal portion of the 

 needles so as to form chambers between the base of the needles and 

 the stem. These chambers, which are not communicating, usually 

 contain from 3 to 30 small wingless insects covered with a white 

 waxy coating. These galls turn brown, dry, and hard on the trees 

 after the insects have escaped, and they may persist for many years. 



The alternate host is Douglas fir, on w^hich these gall lice appear 

 as small cottony tufts on the underside of the needles. Their feeding- 

 punctures cause the needles to turn yellow in spots. Sometimes the 

 damage is so severe as to cause a browning and premature shedding 

 of the foliage. 



The seasonal history is very complicated. The form found on the 

 Douglas fir needles during the winter represents hibernating females 



