INSECTS INJURIOUS TO THE SPRUCE. 22% 
cylindrical bark-borers, belonging to the coleopterous family Scolytide ; 
three species, Pityophthorus puberulus, Xyloterus bivittatus, and Xyleborus 
celatus, being the principal aggressors. 
That the disease was not due to fungi has been shown by a thor- 
oughly competent botanist, Prof. Charles H. Peck, of Albany, N. Y. 
That it was not due to extremely cold weather in winter is probably cer- 
tain from the fact generally observed by us that spruce and fir forests, 
over any given area, are not universally killed, as among groves of dead 
spruces and firs many living perfectly healthy trees exist, while the pines 
and hemlocks have been unharmed. By cutting down portions of for- 
ests and thus letting in cold severe winter blasts, general and wide- 
spread destruction of entire forests may ensue, as has been shown to 
have been the case in France. Why pine trees should have, in general, 
escaped the ravages of these beetles, all of which we have found in 
greater or less abundance under the bark of dead pines, and especially 
in dead stumps, we cannot explain, except from the well-known fact that 
most vegetable-eating insects prefer one species of tree and retain that 
preference for successive gelerations. 
Remedies.—W hen a growth of these trees is invaded by insects boring 
in or under the bark, the loosened bark should at once be stripped off 
and burnt. If the tree is dead it should be cut down and the bark 
stripped off and at once used: for firewood, even if the wood is kept for 
future use as fuel. Trees infested by caterpillars may leave out again 
and gradually assume nearly their original health and vigor. But the 
best remedies are those of a preventive nature. In the present case, 
though the evil is apparently diminishing in Maine, our observations 
taught us that the dead firs and spruces wherever examined are teeming 
with thousands and even millions of small bark beetles in all stages of 
growth. It would therefore be wise to prevent any further spread of the 
evil by cutting down dead spruce and fir timber and selling it off this 
winter for fuel. Forests should be thoroughly cleared, and even pine 
stumps should be barked and the bark burned, for, as already stated 
(p. 175), we have taken thousands of these spruce beetles from under 
the bark of white-pine stumps. In fact, stumps, in the summer succeed- 
ing the falling of the tree, are a general resort for all sorts of destructive 
boring insects; and should it be too expensive a matter to pull up such 
stumps, if the bark is torn off, the naked stump will be much less fre- 
quented by noxious insects. 
We will now proceed to an enumeration of the insects known to be 
more or less destructive to spruce and fir trees. 
AFFECTING THE TRUNK. 
1. THE PINE LONGICORN BORER. 
Monohammus confusor Kirby. 
Order COLEOPTERA; family CERAMBYCID&. 
This common and pernicious borer has been described and figured on 
pages 152-156. It occurred under the bark of dead spruces at Bruns- 
