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(b) Found in limited numbers and causing secondary injury as fol- 

 lows : Bark beetles on walnut, cherry, backberry, elm, mul- 

 berry and ash ; bark-boring grubs on oak and chestnut. 

 (2) Insects not causing the immediate death of the tree: 



(a) Found doing serious damage to timber as follows: Carpenter 



worm on oak ; wood borers on hickory ; powder post borers 

 on hickory. 



(b) Injury to foliage: Nearly all species of trees found affected 



by one or more of the following forms, of which all except 

 the cottony maple scale cause little damage : Leaf eaters, 

 leaf miners, leaf rollers, saw flies, scale insects and gall flies. 



The bark and wood borers can usually be detected by pits or deposits 

 of fine sawdust around the holes. About the only remedy is to remove 

 the infected trees at such times as will prevent the hatching of the larvae. 

 Damage due to leaf insects is usually so slight that it may practically be 

 disregarded. 



Fungi. — Fungi attack trees in several ways. Some kill the roots, 

 others grow upward from the ground into the trees and change the sound 

 wood of the trunks to a useless, rotten mass or leave only a hollow shell. 

 The spores of others come in contact with every part of the tree as they 

 float about through the air. These spores find a very suitable place for 

 germination if they fall on wounds. By removing infected trees and de- 

 stroying old logs fungous, diseases may be fairly well controlled. 



Wind. — Wind-blown timber frequently exists in open or unprotected 

 stands and in moist places where root systems are shallow. Trees weak- 

 ened by fire, fungous and insect attacks are easily broken off. Of course 

 the mature trees may be partially or wholly utilized. The greatest dam- 

 age is done to those for which there is no immediate use. 



Woodlots which have been unprotected from the time they were com- 

 paratively small usually have their own windbreaks made by the develop- 

 ment of numerous side branches. A strip a few rods wide along exposed 

 margins of woods should always be kept as dense as possible. The de- 

 velopment of brush and undergrowth should be encouraged. Unless there 

 are others to take their places no trees should be cut in this protective area 



Should it be necessary to plant a wiudbreak it is best to employ two 

 species, one a rapid grower to provide early protection, the other of slower 

 growth to make a permanent and more efficient shield. Carolina poplar, 



