Insects Bred from American Larch — 15 
of the trees have reached their maximum growth — have 
become matured — and some such trees are deteriorating 
more or less rapidly. The presence of the excellent breeding 
places offered by the girdled larch had resulted in an increase 
of many insect enemies — several of which have increased 
beyond the danger level. These are already successfully 
attacking and killing not only the trees weakened by strip- 
ping off part of the bark but also apparently have in the last 
year or two killed a number of trees which were over-mature 
but were otherwise uninjured. Indeed the conditions here 
are in many respects similar to those reported by Swaine 
(11) in a larch wood near St. Anne’s, Que. There several 
trees had been allowed to remain in the forest after felling 
and these had acted as an excellent breeding place for a 
number of scolytid beetles. Several of these were bred up 
to such numbers that they were able to attack and kill the 
living larches remaining. Of the five bark beetles breeding 
in this larch, including Dendroctonus simplex, Ips balsameus, 
Ips caelatus, Dryocoetes autographus and Dryocoetes sp., 
Swaine considers only the first two as serious enemies of the 
larch. 
In the larch woods at Crittenden, the trees which had been 
girdled by farmers in obtaining bark, had acted in much the 
same manner — as incubators for a number of insects breed- 
ing in dying or dead larch. The numbers of several of these 
had increased beyond the danger level and they were able to 
attack and kill trees over-mature and deteriorating. Several 
of the trees from which most of the material for this study 
was derived had apparently been killed in this manner. 
In our study Trees I and X, as described later, were trees 
weakened by over-maturing and their death is believed to 
have been caused or at least much hastened by insect work. 
Insects found in both of these trees and in others under 
nearly similar conditions included the scolytids Polygraphus 
rufipennis and Eccoptogaster piceae, the cerambycid Asemum 
moestum, always working very near the base of the tree, and 
the melandryid Serropalpus barbatus. Dendroctonus sim- 
plex was present in the bark of the basal twenty feet of the 
