Carpenter Ants are very common in the NW. These ants belong to the largest genus (Camponotus) in the Family Formicidae.
Worldwide there are over 1000 species of Carpenter Ants–not all are wood destroying but when they are, they can do a lot of damage to wood structures. In North America there are about 20 species. In the NW we have mainly two of concern: C. Modoc and C. Vicinus. The “C” stands for Camponotus–the genus.
C. Modoc is pretty easy to recognize–these ants are pretty much all black and they are often bigger than any other kind of ant you are likely to find in the NW–especially in healthy colonies. Seeing these ants hanging out around your yard or in your home is always reason for concern and a Licensed Structural Pest Inspector should be consulted. It is a really good idea to capture a specimen or two in a zip-lock bag to show the inspector when they arrive.
C. Vicinus ants are a little more difficult to distinguish because they can vary from partially red and mostly black to mostly red and some black. This coloration makes it easy to confuse them with Thatching Ants. Thatching ants can be a nuisance but are generally considered beneficial in the environment. These ants rarely invade homes but have been known to nest in wall cavities and other hollow structures of homes.
Because Thatching Ants are not usually a concern in homes, when you see large ants streaming in and out of a home it is easy to think that they might be C. Vicinus, Carpenter Ants. All species of Carpenter ants have a smooth “back” or dorsum–no dents or indentations that would indicate that it is some other kind of ant. Seeing the notch on the dorsum of an ant requires some magnification–and difficult to determine with the naked eye.
Here is a picture of some Thatching Ants that were found in a porch structure—-there were hundreds of them streaming in and out of the opening under the floor boards. Pretty easy to think they might be Carpenter Ants.
If you look close though, at the back of the ant from the side, you can see clearly that the back is not smooth—-it has a notch–consistent with being a Thatching Ant and not a Carpenter Ant.
This distinction makes a huge difference in protocols for treatment–including whether any treatment is necessary at all.
By Charles Buell, Real Estate Inspections in Seattle
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