THE PINE INVESTIGATION. 349 



I found that many trees were then dying;, and that the trouble 

 had spread some since I was there the previous June, but only 

 as a slight extension around the borders of the groups of dead 

 trees. Upon examining the dying trees and those that were only 

 showing slight indications of weakened vitality, I found the liv- 

 ing bark on the lower portion of the trunk infested with great 

 numbers of the spruce bark beetle (Polygraphus rufipenrds} 

 which indicated that this species was the cause of the continued 

 dying of the trees, but upon felling some of the trees thus 

 affected, it was found that they had been previously attacked 

 (in 1892) by the destructive bark beetle, and that this species, 

 and not the spruce bark beetle, was the prime cause, although 

 the trees doubtless would have recovered, had it not been for 

 the attack of P. rufipennis. 



In distributing the beneficial Olerid in the timber on the 

 summit of the mountain, practically the same conditions were 

 found, as at other parts, i. e. the bark of all the trees that died 

 the previous summer and fall, and of those that were then 

 dying, was literally filled with the spruce bark beetle (Poly- 

 graphus rutipinnis) in all stages; while the destructive pine 

 bark beetle, (Dendroctonus frontalis) in every case observed 

 was dead. 



Although examples of the turpentine beetles (Dendroctonus 

 terebrans) were observed flying in the spruce forests and evi- 

 dence was found in the stomach of trout 1 that they had recently 

 occurred here in great numbers, only a single example was 

 found mining in the green bark, and this had attacked a stump 

 of a recently felled tree. 2 None were found attacking living 

 trees as in the pines. 



CONDITIONS IN GRANT COUNTY. 

 SPRUCE. 



Practically the same conditions were found on May 23d, near 

 Baird, in Grant county, as in Randolph county, except that 



1. The stomachs of trout caught at the time were found to be literally crammed with 

 scolytids, consisting principally of Dendroctonus terebrans. Polyqranhus runvennis and 



^Xyloterus bivittatus. 



2. Further study of this species shows that it is closely allied if not Identical to 

 Dendroctonus ruflpennis, 



