22 Thirty-first Report oy the State Museum. 



a few feet high, rapidly tapering, and coated with lichens ; the branches are 

 long, straggling, crooked, and interlaced, the whole forming a hedge-like m^ss 

 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 

 can live ; but they are the constant dread of tourists who visit the unfrequented 

 peaks of the Adirondacks, for they are passed only with the utmost difficulty 

 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, 5 ' 

 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 in a 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, 

 excavates 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 larvae 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 larva advances 

 in its course, it increases in size and the diameter of its furrow increases in like 

 manner. The larvae 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. 



