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ing and lumbering- methods, mining operations, forest fires, and 

 diseases of trees. 



Influence of fanning methods. — I found that, in addition to the 

 girdled timber contributing to the multiplication of dangerous insect 

 enemies of forests, the clearings made in the midst of primitive for- 

 ests by the settlers and farmers expose the trees on the borders of 

 such clearings to abnormal influences, which weaken the vitality of the 

 matured timber. The destructive insects and their allies, breeding in 

 the girdled trees, emerge and attack these weakened ones, and with 

 this additional material, and most favorable conditions for their multi- 

 plication and spread into the healthy forest, a trouble is often started 

 which results in the destruction of vast quantities of timber. 



Influence of lumbering methods. — The abundance of timber in this 

 great forested area and the cost of transporting the products to market 

 leads in most cases to wasteful lumbering methods, only the best timber 

 suitable for special purposes being taken. The remainder, which in a 

 short time would be just as valuable for other purposes, is left with 

 scarred trunks, broken tops and branches, and deprived of the pro- 

 tective environments under which it had developed. The ground is 

 strewn with tops, branches, and trunks of the felled timber, which, 

 with the injured standing trees, furnish tne most attractive breeding 

 places for all bark and wood infesting insects. If the cutting is con- 

 tinued from year to year in the same locality the insects, upon emerg- 

 ing from the debris of the old cuttings, migrate to that of the new, and 

 do not invade the healthy or undisturbed forests. If, on the other 

 hand, cutting is discontinued and the debris is not destroyed by fire, 

 there is great danger of the insects, upon emerging, attacking the 

 healthy timber in the surrounding forests and continuing their rav- 

 ages there. 



The relation of forest fires to depredations by insects. — This is a sub- 

 ject to which little attention has heretofore been given. My observa- 

 tions in the fire-swept areas in the Northwest has, in addition to 

 previous observations in West Virginia, convinced me that this is a 

 problem of considerable importance. Trees dying from injury by 

 fires furnish favorable breeding places for vast numbers of destructive 

 and other bark and wood infesting insects. Those slightly injured 

 and weakened in vitality are prevented from recovery by the attack 

 of bark beetles, which are ever ready to take advantage of any oppor- 

 tunity to overcome the resisting forces of their favorite host plants. 

 Thus the most favorable conditions are offered for the multiplication 

 of insect depredators, which, through their augmented power in 

 increased numbers, are capable of extending their ravages into the 

 healthy forests. Fire wounds at the bases of living trees also lead to 

 serious trouble and losses of the most valuable timber. These wounds 

 give entrance to Cerambycid and Buprestid heartwood borers, black 



