ENTOMOLOGY 313 



The White Pine Weevil. The abnormal development of white 

 pine trees as the result of successive attacks on the terminals of the 

 saplings and young trees by the white pine weevil is an element of 

 loss of considerable importance, especially in mixed stands and in 

 open pure stands of this timber. The value of such trees is reduced 

 from 20 to 50 per cent below those of normal development, and there 

 is an additional loss from the effect of their spreading branches or 

 crowns in the suppression or crowding out of trees which would oth- 

 erwise occupy the space thus usurped. There are many other exam- 

 ples of insects which damage the wood and bark of living trees, but 

 those mentioned should be sufficient to demonstrate the importance 

 of insects in this relation. 



INSECT INJURIES TO THE WOOD OF DYING AND DEAD TREES. 



Timber dying from insect attacks and other causes, including 

 fire, disease, storms, etc., is attacked by certain wood-boring insects 

 which extend their burrows through the sound sapwood and heart- 

 wood, and thus contribute to the rapid deterioration and decay of a 

 commodity which otherwise would be available commercially dur- 

 ing period of from one to twenty years or more after the death of 

 the trees, depending on the species of trees and on the character of 

 the product desired. This loss often amounts to from 25 to 100 per 

 cent during the period in which the dead timber would otherwise be 

 almost as valuable as if living. 



CONIFEROUS TREES. 



Sawyers. One of the most striking examples of the destruction 

 or deterioration of the wood of dying and dead timber, familiar to 

 all lumbermen, is the injury to fire-killed and storm-felled pine, fir, 

 spruce, etc., caused by boring larvae known as "sawyers." These 

 borers hatch from eggs deposited by the adult beetles in the bark of 

 the dying trees, and after feeding on the inner bark for a time they 

 enter the solid wood and extend their large burrows deep into the 

 heartwood. Fire-killed white pine is especially liable to this injury 

 and is often so seriously damaged within three or four months dur- 

 ing the warm season as to reduce the value of the timber 30 to 50 per 

 cent. The shortleaf, loblolly, and longleaf pines of the Southern 

 States are damaged to a somewhat less extent, but instances are 

 known in which more than one billion feet of storm-felled timber 

 within limited areas were reduced in value 25 to 35 per cent within 

 three months after the storm. The fire-killed and insect-killed sugar 

 pine, silver pine, and yellow pine of the western forests are also dam- 

 aged in a similar manner and the value of the product greatly re- 

 duced within a few months after the trees die. The aggregate losses 

 from this secondary source in the coniferous forests of the entire 

 country contribute largely to the annual waste of millions of dollars' 

 worth of forest products which otherwise might be utilized. 



Ambrosia Beetles. ."Wood-boring insects of another class, 

 known as timber beetles or ambrosia beetles, cause pinholc defects, 

 principally in the sapwood, although some of them extend their bur- 

 rows into the heartwood. These insects make their attack in (ho 

 early stage of the declining or dying of the tree, or before the sap- 



