INSECTS INJURIOUS TO THE SPRUCE. 225 
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 diame- 
ter. As soon as the eggs are hatched, the larve 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 visible to the 
naked eye; but as the larva advances in its course it increases in size and the diame- 
ter of its furrow increases in like manner. The larve 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 origi- 
nal furrows appeared to be less than 4 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 excavated longitudinally or parallel to the axis of the 
trunk, while in the case of the baisam-destroying beetle the original furrow is exca- 
vated at right angles to this axis, and therefore cuts off or destroys the vital action 
over a much broader space. 
“The destruction of the balsams was not limited to the single grove in which it was 
first observed. In several places along the road between Summit and Jefferson dead 
and dying balsams were noticed; but the affected trees were not very numerous, and 
it would not be a difficult matter, with prompt and united action, to arrest the prog- 
ress of the mischief. If each man, on whose land the balsams grow, would, as soon 
as signs of the presence of the trouble are manifest, cut the affected trees, strip off the 
bark and burn it, he would, by so doing, destroy the colonies of larvie and prevent 
the further spread of the mischief. It is not at all probable that trees once attacked 
and showing signs of death can be saved, and it would be far better to cut them im- 
mediately than to allow them to remain as nurseries for these tiny marauders.” 
The spruce and firs in the Adirondacks, however, seem in general less affected than 
in Maine. Mr. John H. Sears, an observing botanist of Salem, Mass., who made a 
trip there late in the summer of 1881, writes me that ‘‘the spruce and other coniferous 
trees are remarkably healthy, noticeably so from Ticonderoga, Essex County, through 
Clinton County to Rouse’s Point; and in Canada northward to Montreal from Lyon 
Mountain to Chateaugay there are large and handsome specimens over 3 feet in diam- 
eter. 
Similar destruction of spruces in Maine in 1818.—From Mr. William 
Alexander, of Harpswell, we learned that ‘about eighty years ago” there 
was a Similar destruction of the spruce growth upon the same farm (his 
father’s) as we visited, and it was his impression that his father ac- 
15 RIL 
