We have been using pressure treated lumber for decades to resist insect damage. It works great against termites and beetles, both organisms eat wood. But we have more wood destroying organisms than these two.

Carpenter ants are easy to identify, in the northwest the most common one is called Modoc, it is a large black and sometimes with slightly reddish legs.
Since these insects do not eat wood, it doesn’t matter what you treat the wood with, you must use another form of control. The recommended pesticide for carpenter ants is a EPA registered chemical, and you can not buy it unless you are a licensed exterminator. This stuff is so toxic it can only be applied 2x a year by law. The ant killer in the hardware store is woefully inadequate, and rarely does much but shorten the life of the people that use it. (it does not control carpenter ants for sure!)
These ants in the yard are of little concern, they are the natural way to break down stumps and dead trees. It is only an issue when they decide to nest in homes.
If you have an issue with carpenter ants or any structural pest, give us a call, we give out free advice on everything related to the care and maintenance of your home.

Carpenter Ants have an evenly curved “thoracic dorsum”, this is the back of the insect.

The most common member of this family is Modoc; it is black with reddish colored legs, but color is not a good indicator as some types have red parts. These ants are often found moving along foraging lines about 1 foot apart. Trees, fences and firewood are all regular paths that they are known to use.

Damage in the Home
Carpenter ants will damage homes by nesting in them. The will dig out tunnels in wood to expand their living spaces and can lead to structural damage. The infestation in the home usually is a satellite colony, with the main one within a hundred yards or more in a stump or other decayed wood. When colonies start to establish themselves in homes, they may start small (a few hundred members) but can grow to several tens of thousands. There can be 20 or more satellite colonies.

Making your Home Resistant to Carpenter Ants
Stumps, firewood:
Take care when storing firewood. This is a favorite nesting location for Carpenter ants. Always keep wood elevated and covered from the rain. A wet pile of firewood in contact with the ground is an ideal infestation location. Stumps left in the yard are common locations for colonies.

Never allow plants to make contact with the home. Trees and shrubs provide natural paths for insects and are frequently foraging sites.

Wood/Soil contact:
It is a conducive condition for pests when wood touches soil. Wood should rest on concrete or other suitable support, and when it is in direct contact with the ground pressure treated lumber is recommended. Beauty bark or other landscaping is often piled too high next to homes. This can lead to rot/decay and lead to a Carpenter ant infestation.

Crawlspaces and attics need adequate ventilation to keep the moisture content low. If the ventilation is not adequate, there will be biogrowth (mold, mildew or fungus) and create conditions that encourage infestations. Vapor barriers are recommended in crawlspaces. This will help keep the framing under the home dry and provide a barrier to discourage pests.

Points of Entry:
Check for holes in the exterior of the home, where pipes and electrical wires enter. Doors, windows, foundation cracks, siding and trim are all common locations for ants. Seal these areas with caulk or other suitable materials to discourage entry.

 Read more about Carpenter ant control
 Carpenter Ant Update, PCT Magazine April 2002, L. D. Hansen.
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JJ Greive

JJ & Suzanne are both licensed, highly skilled inspectors and educators. We are the authors of our class curriculum, and truly enjoy sharing this with our students


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