ILLUSTKADED GUIDE. 



123 



fuel. This is called pollarding, and the engraving ] 15, 

 p. 125, gives an excellent idea of the process. 



OHAPTEE XYIII. 



INSECTS INJURIOUS TO TREES. 



I will not attempt to give the names and descriptions 

 of all the insects which commit 

 depredations on forest-trees. Their 

 name is legipn, and man, in the 

 woodlands, is almost impotent as 

 regards these^^tiny but terrific 

 enemies. 



Still, there is one point I must 

 insist on. The periodical invasion 

 by insects of countries where they 

 have been, heretofore, hardly per- 

 ceptible, is always due to a tan- 

 gible though passing cause. Thus, ^4^x 

 for example, an excessively mild 

 winter suffers a host of larvse, a 

 large proportion of which brutes 

 is generally destroyed by the cold, 

 to pass the winter safe and sound ; hence, in the 



109.— Badly pruned tree. 



following summer, an extraordinary development of 

 insect life. On the other hand, this unusual develop- 



