Although their name suggests that they would be an industrious addition to your home, these pests can cause significant damage as they tunnel through wood structures to build their nests. They do not eat wood but burrow into it to make their home. The two dominant species of carpenter ants in Southern Ontario are the Northern Carpenter Ant (black abdomen with reddish thorax and head) and the more common Pennsylvanian Carpenter Ant (completely black).

Characteristics of Carpenter Ants

• Carpenter ants are separated into Three castes: Major workers (Soldiers), minor workers, and reproductives.  Each caste is tasked with specific jobs inside their colonies.
• Workers are the most seen in a residence and range in size from 6 – 12 mm.
• Mature colonies contain approximately 3000 or more individual ants.
• Carpenter ant colonies can consist of one large primary nest or there may be additional satellite nests that are related to the main nest.

How do Carpenter ants invade my home?

Winged reproductive are expelled from the nest when conditions are favourable in the spring or early summer.  After the mating flight, the new queen will search out water damaged wood to burrow into to start her nest.  The queen will tend to the first brood until they become adults and can take over the maintenance of the nest while the queen focuses on egg laying.  Once the nest matures then the queen will start producing male and female reproductives to start the process again.  The presence of the flying caste is a good indication of a mature nest that has been active for 7 or more years.

They can also relocate into your home when a nearby nest is disturbed.

Where is the Carpenter ant nest in my home?

Carpenter ants may appear foraging in your home as early as February.  Later in the spring they will focus on foraging for food outside of the home while the nest is burrowed deep into your exterior walls.  You may no longer see ants inside your home at this point but it doesn’t mean that the nest has moved on.  A simple inspection of the exterior of the home in late May or June can easily locate a nest as workers return with food for the colony.

Carpenter ants are commonly found in areas of the home that have experienced water damage such as: kitchens, bathrooms, fascia, windowsills, door sills or foundation sills.  They can often be heard chewing inside the walls to expand their galleries.

How do you treat Carpenter ant nests?

Carpenter ant nests can be difficult to locate and treat since they are hidden away out of sight in your walls.  Most ant species are highly motivated to follow pheromone food trails and feed on ant bait poison. Unfortunately, Carpenter Ants do not share that same trait.  This results in ant bait not being a good solution to exterminate a Carpenter Ant infestation.  Often homeowners will place ant bait stations each spring as the ants appear and believe that the nest is fixed when the ants focus their foraging habits outside.  Unfortunately, this is not correct.  The ants have only changed their habits and are continuing to damage structural members of the home.

Proper treatments for Carpenter ants involve the application of a residual insecticide through the home as well as insecticide being injected into the walls to permeate the nest and kill the queen.  A dead queen is a dead nest!