23 



bark-borer (Asemum nitldum)^ which has similar habits to those of 

 the hemlocli bark-borer; and (3) the Sitka spruce spanworm, which 

 defoliates and kills the trees over large areas. 



THE CEDARS. 



The California Redmood has a special enemy in the sequoia bark- 

 beetle {Phlmosinus sequoisd Hopk. MSS.) 



The Giant Ariorvitx has an enemy in Callidium janthinum, and 

 the Eastern Arborvitae one in Ilylotrupes Ugneus, which infest the 

 living trees and either kill them or cause serious defects in the wood. 

 The other true cedars, the Monterey Cypress, and some of the Western 

 and Eastern junipers, have a number of bark- and wood-boring enemies, 

 which are more or less destructive. 



The Western, grand, noble white, and Shasta firs, and the Eastern 

 balsam firs are attacked by several destructive bark-beetle enemies, 

 which either kill the trees or cause serious gum-spot defects or decayed 

 places in the wood. 



THE OAKS. 



The insect fauna of the oaks is very large, probably exceeding in 

 number of species that of the pines. Those noted for their especially 

 destructive attacks on living trees are the carpenter worms {Prio- 

 noxystus spp.), which bore into the bark and wood and not only cause 

 serious worm-hole defects, but by successive attacks cause the death 

 of part or all of the tree. Their burrows give entrance to wood- 

 decaying fungi which soon render the heartwood worthless for com- 

 mercial purposes. The giant root-borer {Prionus laticoUis) is another 

 enemy of Eastern oaks in general, which is enormousl}' destructive to 

 large and small trees in forest, park, and lawn; but it would seem that 

 its work is rarely recognized, and that the magnitude of the damage 

 is not generally understood. The large, white, elongate grubs bore 

 in the roots and bases of the trees, causing one or more of the larger 

 roots to die. These holes and the burrows made by the carpenter 

 worms give entrance to other wood-boring insects and wood-destroying 

 fungi, which rapidly extend and complete the destruction of the injured 

 parts. This decay often extends into the base of the trunk, destroy- 

 ing the heartwood and thus causing the tree to be hollow and worth- 

 less. The decayed wood of the roots and base of the tree also furnishes 

 fuel for forest fires, so that the trouble started by the giant borer, and 

 extended by other insects and fungi, is made conspicuous by a great 

 blackened wound, which is more often than otherwise supposed to be 

 due to fire alone. Trees are often killed outright by this root destroyer, 

 but the work is usually so obscure that the trouble is often blamed to 



