Question
Mr. Hyland

I noticed several rather large holes in the trunk of this tree. The only pests I have seen around the tree are the large what I believe are called Carpenter Ants.  There are several not exactly mounds but a build of very fine material of the same color as the inside of the bark of this tree.  The texture of this build up is very fine like when the ants make a mound.  Have you ever heard of these large black ants eating or nesting in a live tree and making large holes in the trunks.  I am very worried about this tree.  I realize that Oaks are usually a hearty tree, but I would hate to neglect doing anything that might turn into a terminal problem for this tree.  It is one of a matched set.  It sits on one side of the front lawn and there is another on the other side that I believe is older yet.  Please give advice if at all possible.

Sincerely
Ann

Answer
Carpenter ants nest in trees in one of two situations: 1) in rotted, decayed wood or 2) in the center heartwood section of the tree. In neither case are they harmful to the tree. Control is unnecessary for the tree's health, as the ants are taking advantage of preexisting soft, weak wood to establish their colony. Insects, disease, or environmental conditions such as drought are often responsible for weakening and killing limbs or sections of trees. This allows wood rot to set in, which results in wood decay, giving carpenter ants the opportunity to colonize the tree. Carpenter ants use knots, cracks, holes, and old insect tunnels to gain access to these areas.

Control of carpenter ants in trees is warranted if there are indications that ants are entering homes from colonies in trees. If there is evidence of this, the best control is to bait the colony.
Baits, such as Terro. Baits tend to be slower-acting than other forms of carpenter ant control, but they are easy to apply and give good results, especially when the nest can't be located. The ants themselves will carry the bait back to the nest, which usually provides colony elimination.

There are a few baits available to nonprofessionals for carpenter ant control. Most retail products are liquid or granular formulations containing hydramethylnon, sulfluramid, abamectin, or boric acid. An inexpensive liquid bait of 1% boric acid in a 10% sugar water solution can be mixed at home, but it is very slow acting and must be constantly replenished. Baits vary a great deal in their effectiveness. Carpenter ants have complex food preferences, and some of the sugar-based baits will not be attractive to the ants long enough to be successful.