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INSECTS INJURIOUS TO THE PINE. tT 
there are usually four galleries leading off in opposite directions and 
running obliquely to the grain of the wood, but curving, commonly, till 
they obtain a longitudinal direction. And from these numerous smaller’ 
and irregular wavy galleries branch off, at right angles or nearly so, and 
overspread the whole surface with a seemingly confused multitude of 
little furrows. The bark being quite thin in the young trees to which 
these beetles resort, their galleries are excavated mostly in the wood, 
the surface of which is deeply grooved whilst only a shallow impression 
is made on the inner surface of the bark. But at the end of each of 
the lateral galleries, a deep cavity will be noticed, sunk in the bark, in 
which cavities the insects repose during their pupa state. 
The accompanying figure of the tracks of these beetles handsomely 
illustrates some of the facts which have already been stated above un- 
der the Wood-engraver bark-beetle, and it may interest the reader to no- 
tice some of the habits of these insects as shown by this figure.* In its 
upper half two leading galleries are seen running parallel with each other 
and so near together that no adequate space exists between them for 
any young larve to form their burrows there without encroaching upon 
each other or crossing the tracks already made. The parent beetles ap- 
pear to have been aware of this, and accordingly so disposed of their 
eggs that all their young with but two or three exceptions mined out- 
wards, traveling away from each other. Again, on the outer side of the 
left gallery two notches are observed, in which no eggs appear to have 
been placed, the parent beetle probably perceiving, what the figure in- 
dicates, that there was not suitable room to the left of these notches to 
duly accommodate all of the other larvee that would traverse that spot. 
Furthermore, it will be noticed that of the burrows leading off to the 
right, above the large knot or nuptial chamber, the worm which exca- 
vated the fourth one, soon after commencing his journey perceived that 
the course he was pursuing would run his track into that of the third 
one. He hereupon abruptly alters his course, bearing directly away from 
‘the track of this neighbor until he has attained a suitable distance 
therefrom, and he then travels forward again, keeping at this exact dis- 
tance from his neighbor’s path. But this soon brings him into prox- 
imity with another neighbor upon the other side; and he now becomes 
‘aware of the fact that he is between two paths that are approaching 
each other, and that will consequently come so near together forward of 
him that he cannot proceed onward without running into one or the 
other of them. In this dilemma, to encroach the least that is possible 
upon his neighbors, he makes an abrupt turn. so as to go square across 
one of these tracks. But this only serves to bring him into similar 
proximity with another track, and after this comes another and another; 
and now he reaches a fifth one, running in a different direction, requir- 
ing another alteration of his course to cross it at right angles. But we 
need not follow this subject further. Others also of these galleries, 
* Not reproduced. 
