170 



LETTERS TO MR. MARTIN [CHAP. XVH. 



I should conjecture that the trees were not in absolutely 

 perfect health, and this is the state of things the beetle pre- 

 fers for its attack. Injured boughs, or moderately recently- 

 fallen boughs, or, above all, felled elm trunks in which 

 there is still sap, but not flow enough to stifle the little 

 maggots, are the very headquarters of infestation, and it is 

 quite worth while to have such felled trunks peeled and the 

 bark destroyed, or they will be the nurseries of great mis- 



Beetle, much magnified (from " Forest Protection," by W. R. Fisher) ; 

 workings in elm bark from life. 



FIG. 35. ELM-BARK BEETLE, SCOLYTUS DESTRUCTOR, OLIV. 



chief. If you will supply me with more detail I will with 

 great pleasure give my very best attention. 



April 5, 1897. 



The little larvae came safely yesterday and the specimens 

 of bark this morning. Necessarily when the attack has 

 been going on so long the burrows intersect each other 

 so very much that they cease to show the typical pat- 



