314 INSECTS AFFECTING VEGETATION 



wood has materially changed from the normal healthy condition, 

 and often in such numbers as to perforate every square inch of wood. 

 Thus the wood is not only rendered defective on account of the pres- 

 ence of pinholes, but the holes give entrance to a wood-staining fun- 

 gus which causes a rapid discoloration and produces still further de- 

 terioration of the product. 



The sapwood of trees dying from the attack of other insects or 

 from fire, storm, or other causes is often reduced in value 50 per 

 cent or more, and in some cases the value of the heartwood is reduced 

 in a like manner from 5 to 10 per cent. 



Pinhole Borers in Cypress. An example of the destructive 

 work of insects which attack dying and dead trees is found in the 

 cypress in the Gulf States, where these trees are deadened by the 

 lumbermen and left standing several months, or until the timber is 

 sufficiently dry to be floated. Upon investigation it was found that 

 trees deadeneu 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. 



HARDWOOD TREES. 



Roundheaded Borers, Timber Worms and Ambrosia Beetles. 

 The principal damage to dying and dead hardwood trees is caused 

 by certain roundheaded wood-borers with habits similar to the saw- 

 yer, by the timber worms mentioned as damaging living timber, and 

 by ambrosia beetles having habits similar to those that attack the sap- 

 wood and heartwood 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. 



INSECT INJURIES TO FOREST PRODUCTS. 



Damage is caused by various species of insects which are at- 

 tracted by the varying conditions prevailing at different stages dur- 

 ing the process of utilizing the forest resources, from the time the 

 trees are felled until the logs are converted into the crude and fin- 

 ished product and until the latter reaches the final consumer, or 

 even after it is placed in the finished article or structure. As a re- 

 sult, 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 investiga- 

 tions 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 dif- 

 fers from that resulting from insect damage to standing timber in 

 that it represents more directly a loss of money invested in material 

 and labor. 



CRUDE PRODUCTS. 



Roundheaded Borers, Timber Worms, and Ambrosia Beetles. 

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

 eawlogs, etc., is subject to serious damage by the same class of in- 



