338 AMERICAN FORESTRY 



attacked by the mountain pine beetle the broods were being destroyed by wood- 

 peckers and other natural enemies, and that therefore the effort to control the 

 beetle depredations were a success. In 1910 no timber died. 



These examples have shown that outbreaks of beetles in the forests can be 

 controlled at moderate expense and that it is perfectly practicable for the best 

 methods to be applied by private owners. 



INSECT INJURIES TO THE WOOD OF LIVING TREES 



A certain class of insects attack the wood and bark of living timber and 

 and while they do not contribute materially to the death of trees, or give much 

 external evidence of their presence, they produce wounds in the bark and worm- 

 hole and pin-hole defects in the wood which result in a considerable deprecia- 

 tion of commercial value. These defects are not detected until the trees have 

 been felled and the logs converted into lumber. Thus the expense of handling 

 and manufacture is added to the loss from defective material. Among insects 

 of this class is the oak timber worm, which enters the wood of the trunks of 

 the living trees through wounds in the bark and at the base of broken or dead 

 branches and extends its burrows in all directions through the solid hard wood. 



Another is the chestnut timber worm, which damages the chestnut in the 

 same manner throughout its range. It is estimated that the reduction in value 

 of the average lumber product at any given time is not far from thirty per 

 cent. This insect also attacks oaks, and especially the red oak. 



Carpenter worms are another enemy of the oak, making holes through the 

 hard wood of the best part of the trunk, sometimes one and five-tenths inches 

 in diameter by seventy-five hundredths of an inch. Other insects of this class 

 noted by Dr. Hopkins are the ambrosia beetles, to which is due one of the 

 commonest defects in white oak, rock oak, beech, whitewood or yellow poplar, 

 elm, etc., known to the lumber trade as "grease spots," "patch worm" and 

 "black holes" ; the locust borer, turpentine beetles and turpentine borers, which 

 are the cause of what is known as basal wounds, or basal fire wounds, in various 

 species of pine: the white pine weevil, which is responsible for the abnormal 

 development of white pine trees as a result of successive attacks on the 

 terminals of saplings and young trees. This list is not complete, but includes 

 some of the most serious enemies of the living forest trees. 



Insects of this class, which cause defects in the wood of living timber, can 

 best be controlled by (1) The utilization of all defective and infested timber 

 that will pay expenses for manufacture into merchantable products: (2) the 

 burning of infested timber and waste material not available for use, including 

 dead and fallen timber to remove the breeding of insects like the oak timber 

 worm and the chestnut timber worm, which go from the dead to the living 

 timber; (3) the prevention of wounds of any kind in the bark of living trees; 

 (4) the prevention of future losses by the practice of improved forestry 

 methods to eliminate conditions favorable for injuries and contribute to a 

 perpetual supply of vigorous, healthy timber to be utilized before it passes the 

 stage of profitable increment. 



INSECT INJURIES TO THE WOOD OF DYING AND DEAD TREES 



Among insects, which by extending their burrows through sound sapwood 

 and heartwood in dying and dead trees contribute to the deterioration and 

 decay of a commodity which otherwise would be available commercially during 

 periods of from one to twenty years or more after the death of the trees, are 

 the sawyers, ambrosia beetles and pin-hole borers in cypress, all of which do 

 extensive injury to the wood of coniferous trees ; and the round-headed borers, 

 timber worms and ambrosia beetles which similarly injure hardwood trees. 



