_ peaks of the Adirondacks, for they are passed only with the utmost difficulty 
| ‘ ws é “ey a Ks ' ay wid 8 EY ¥ 
72 Rega THIRTY-FIRST REPORT ON THE STATE Museum. wo 
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a few feet high, rapidly tapering, and coated with lichens; the branches are — 
long, straggling, crooked, and interlaced, the whole forming a hedge-like mass 
through which anything larger than a rabbit would find great difficulty in pass-— 
ing. Starved by the lack of soil; stunted in its growth by the short, cold 
seasons ; pressed down by the weight of accumulating snow; and bruised and 
cut back by masses of ice and frozen snow hurled against it by fierce blasts of . — 
wind, it can no longer attain its usual size and its natural symmetry of form. 
These mountain thickets of balsam are of interest to the botanist, because they 
show the hardy character of the tree, and its ability to live where few other trees 
ean live; but they are the constant dread of tourists who visit the unfrequented 
and labor. 
The wood of the balsam is of little value for lumber owing to the small size 
of the tree. It contains resin and burns freely, but with a crackling noise. The 
smoke is very penetrating and irritating to the eyes. Near the summits of 
the mountains, however, it is almost the only available wood for camps and ~ 
camp-fires. The bark of this tree furnishes the well-known ‘“ Canada balsam,” 
a clear viscid resin of considerable repute in medicine and much used in : 
mounting objects for the microscope. The resin is obtained from small vesicles : 
or ‘‘blisters’’ in the bark. It is generally more abundant in the thrifty : 
smooth-barked trees of low damp lands than in the stunted growths of the 
mountains. Because of the value of this tree as a producer of balsam, and 
because of its beauty and fitness to adorn parks and pleasure grounds, it ought 
to be cherished and preserved. But like its companion, the spruce, it has its . 
insect and fungoid foes. While at Summit, in Schoharie county, in September, 
I noticed ina small grove of balsams that a dozen or more of the trees had 
recently been killed or were then dying. The leaves had nearly all changed 
their color, but for the most part yet remained on the trees. An investigation 
showed pretty conclusively that an insect was the cause of the death of the 
trees. A minute bark-mining beetle, both in its mature and in its larval state, 
was found between the bark and the wood. The beetle perforates the bark, 
excayates its furrow along the inner surface in a horizontal direction, and deposits ; 
its eggs along the sides of the furrow which is less than one-sixteenth of an inch 
in diameter. As soon as the eggs are hatched, the larvee begin to mine furrows 
of their own at right angles to the original gallery, one part eating their way 
upward and another downward between the bark and the wood. These larval 
galleries are nearly parallel to each other, and are at their beginning so minute 
that they are scarcely perceptible to the naked eye; but as the larya advances 
in its course, it increases in size and the diameter of its furrow increases in like 
manner. ‘The larvz were found (in some instances transformed to the mature 
beetle) each in the larger end of its own furrow. It will be observed from the | 
direction of the original furrow, how powerful an agent for mischief this minute ~ 
beetle is. Its work is carried on in the most vital part of the tree. Three or 
four beetles attacking the trunk at or about the same height, and on different 
sides of the tree, would completely and effectually girdle it and destroy its life. 
Even a single beetle, by extending its furrow entirely around the trunk, would 
accomplish the same result, but no furrows were found thus extended. The 
length of the original furrows appeared to be less than four inches. The beetle 
itself is scarcely more than one line long, and belongs to the genus Tomicus. The 
species is probably undescribed. In the case of the spruce-destroying beetle 
more workers are necessary to kill the tree because the main furrows are exca- 
vated longitudinally or parallel to the axis of the trunk, while in the case of the 
balsam-destroying beetle the original furrow is excavated at right angles to this 
axis, and therefore cuts off or destroys the vital action over a much broader space. 
