The Black Spruce. 



299 



with a large trunk presents a broader field for their opera- 

 tions than one with a small trunk ; or possibly the vigor 

 of the tree may be so impaired by age that it is more readily 

 brought into suitable condition for the habitation of these 

 parasites. Whatever the cause of this selection, no dis- 

 eased condition of the trees was detected except that which 

 was accompanied by and to all appearance was directly due 

 to the insects themselves. Certainly if the tree is at all 

 diseased before its attack the insects must be exceedingly 

 quick to detect it, else they could not be found in abund- 

 ance in trees whose leaves are yet green and whose sap- 

 wood is yet fresh and moist except where stained by their 

 excavations. 



In the vicinity of Lake Pleasant the affected trees are 

 upon the mountain slopes or on dry ridges where the 

 spruces are especially abundant. And we might naturally 

 expect that the insects would be attracted to and carry on 

 their depreciations most extensively in those localities 

 where the material on which they work is most abundant. 

 In the valleys I saw no trees affected by them and yet they 

 doubtless do carry on their destructive work in the low 

 lands where spruces abound. I see no reason why they 

 should not. 



In some localities their ravages have already ceased. 

 On the slopes of an elevation a few miles southwest from 

 Speculator mountain there are two groves of dead spruces. 

 Many trees in both were examined, and, though all the 

 dead ones bore unmistakable marks of the former presence 

 of the beetle, not one could now be found either in the 

 adult or in the larval state. What had caused them to 

 disappear? Surely not the lack of material on which to 

 work, for several large living spruces yet remained. This 

 leads to the consideration of remedies. Doubtle. s there 

 are natural agencies whose free operation has a tendency 

 to check the ravages of these insects and to prevent their 

 excessive multiplication, but there are times and localities 



