64 SOME INSECTS INJURIOUS TO FOEESTS. 



ened at certain seasons of the year were attacked by the. ambrosia 

 beetles or pinhole borers, and that in some cases millions of feet of 

 timber had been reduced 10 to 25 per cent or more in value. (Hop- 

 kins, 19076.) 



HARDWOOD TREES. 



Roundheaded borers, timber worms, and ambrosia beetles. — The 

 principal damage to dying and dead hardwood trees is caused by cer- 

 tain roundheaded wood-borers (Cerambycidse) with habits similar to 

 the sawyer, by the timber worms mentioned as damaging living timber, 

 and by ambrosia beetles having habits similar to those that attack 

 the sapwood and heart-wood of conifers. All of the hardwoods suffer 

 more or less, but the greatest damage is done to the wood of hickory, 

 ash, oak, and chestnut, which are often reduced in value 10 to 25 per 

 cent or more within the period in which it would otherwise remain 

 sound and available for commercial purposes. (Hopkins, 1894a, 

 1904a, 1905a.) 



Insect Injuries to Forest Products. 



Damage is caused by various species of insects which are attracted 

 by the vanning conditions prevailing at different stages during the 

 process of utilizing the forest resources, from the time the trees are 

 felled until the logs are converted into the crude and finished product 

 and until the latter reaches the final consumer, or even after it is 

 placed in the finished article or structure. As a result, additional 

 drains are made on the timber to meet the demand for the higher 

 grades of lumber and for other supplies to replace those injured or 

 destroyed. From the writer's personal investigations of this subject 

 in different sections of the country it is evident that the damage to 

 forest products of various kinds from this cause is far more extensive 

 than is generally recognized. This loss differs from that resulting 

 from insect damage to standing timber in that it represents more 

 directly a loss of money invested in material and labor. (Hopkins, 

 1894a, 1903c, 1904a, 1905a.) 



CRUDE PRODUCTS. 



Roundheaded borers, timber worms, and ambrosia beetles. — Round 

 timber with the bark on, such as poles, posts, mine props, sawlogs, 

 etc., is subject to serious damage by the same class of insects as those 

 mentioned under injury to the wood of dying and dead trees. The 

 damage is especially severe when material is handled in such a man- 

 ner as to offer favorable conditions for attack (Hopkins, 1905a), as 

 when the logs are left in the woods on skidways or in mill yards for 

 a month or more after they have been cut from the living trees. 

 Under such conditions there is often a reduction in value of from 5 to 

 30 per cent or more, due to wormhole and pinhole defects caused by 



