67 



Mr. Fiske presented the following paper, which had been prepared 

 conjointly by Mr. Weed and himself: 



NOTES ON SPRUCE BARK-BEETLES. 



By Clarence M. Weed and W. F. Fiske, Durham, N. H. 



During the summer of 1897 a complaint was received at the New 

 Hampshire College Experiment Station of damage done to spruce in 

 northern New Hampshire, supposedly by a bark-beetle which had been 

 identified by Mr. ¥. H. Chittenden as Dendroctonus rufipennis. In the 

 course of the season two trips were made to the infested region by the 

 writers, and the object of this paper is to give a brief account of the life 

 history and habits of the species and of the damage done. 



In company with Mr. Austin Cary, of Maine, a forester of long 

 experience, a narrow strip of primeval forest in northern New Hamp- 

 shire, about 10 miles long, was explored. The principal trees of this 

 area were hardwoods, birches and maples predominating, but among 

 them were considerable quantities of black spruce. The dead stubs of 

 the latter species, many of them far advanced in decay, were ample 

 evidence that at some previous time it had formed a much larger per- 

 centage of the forest. In the course of the three days that were spent 

 in the woods a great many dead and dying trees were examined, and 

 in almost every case where the bark was still clinging to the trunk the 

 peculiar remains of the Dendroctonus burrows, to be described further 

 on, were discernible. 



In spite of the great amount of damage which has been and is still 

 being done, it was quite difficult to find the insect actually at work. 

 The infested trees would retain their green color until the young larvse 

 had reached their full growth, the beetles in many cases flown, and the 

 space under the bark become so filled with a myriad of the smaller 

 Scolytida3 that it would be impossible to say with certainty to which to 

 ascribe the original attack. On one occasion, however, we had an 

 unusual opportunity to observe the working of the Dendroctonus, and 

 the following is copied with little change from notes actually made in 

 the field : 



In the afternoon of August 5 we came across a group of affected trees. 

 As in those found the day before, they were in various stages of death 

 and decay. On some the leaves would still be dropping, but there 

 would be no sign of the Dendroctonus save the remains of the peculiar 

 burrow already mentioned. Others were in more advanced stages of 

 decay, while a few were still green and apparently healthy, but around 

 their bases would be a fine dust, which seems to be discharged at the 

 very beginning of the burrow, and on the trunks would be the telltale 

 tubes of pitch which guarded its entrance. In one tree in the latter 

 condition the limbs approached near enough to the ground to enable 

 one to climb into it. At a height of about 25 feet the trunk was peeled 



