152 HICKORY. TRUNK — WALNUT ANT. ITS BURROW. 



leries they had extended and connected together by their own 

 mining labors. These passages were extended everywhere 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 Pcnnsylvanica 

 lig?iiperda i fyc.) 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 

 abandon 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 burrows 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 was 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 which 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- 



