^ 856 [Assemble 
leries they had extended and connected together by their own 
mining labors. These passages were extended every where 
through the wood of the trunk and branches, often running out 
even into the small limbs less than three inches in diameter. 
Our other wood-eating or carpenter ants (Formica Pennsylvanica 
ligniperda , #c.) seem to reside only in the dead wood of the in¬ 
terior of trees and in the timbers of our buildings, but this species 
is of a more pernicious character, attacking the sound wood of 
living trees. Its burrows are long narrow passages, never widen¬ 
ed into those spacious apartments which our other carpenter ants 
excavate. Sometimes portions of dead wood in the heart of the 
tree and at its butt will be met with, mined in a different manner, 
large chambers and galleries being excavated which are separated 
by partitions no thicker than pasteboard; and not unfrequently 
a few dead individuals of the Pennsylvania ant, which is a larger 
species, may be found lying in these galleries, showing that these 
apartments were constructed by them and not by the walnut ant. 
And it appears to be a common occurrence for a colony of the 
Pennsylvania ants to establish themselves in the dead wood of 
the walnut, and to be afterwards so encroached upon by the more 
numerous and thriving colony of the walnut ants that they aban¬ 
don or are driven from the tree, for I have never met with any 
living individuals of this species in these cavities, which had 
manifestly at some previous period been excavated by them. 
It has been remarked of one of the European ants (Formica 
fuliginosa ) that the sides of its burrow's are always of a black 
color, and our American ant has a similar habit. It paints the walls 
of its rooms, as we may say, of a butternut or snuff'brown color. 
Huber could not satisfy himself whether the black color of the 
wood occupied by the European ant alluded to w r as caused by its 
being exposed to the air, by some vapor emanating from the 
bodies of the ants, or by its being acted upon and decomposed by 
the formic acid w'hich ants secrete. To us it appears that the 
last of these is probably the cause, for with our species this dis¬ 
coloration is not confined to the surface of the burrow, but pene¬ 
trates through the wood surrounding it on all sides, to the dis- 
