Carpenter Ants

Carpenter AntsCarpenter ants pose a problem to our structures by not eating the wood but burrowing in the wood and excavating it for the colony to habitat and rear their eggs. Most often a colony will establish a nest in decaying wood but once established they extend their tunneling into sound wood. However since the colony consist of a single queen workers are produced at a slow rate and a colony of 2 years may only have 200 to 300 workers. A mature colony can consist of 100,000 ants. Most colonies in a structure are “satellite “colonies sent from a parent colony to dwell in structures and may consist of Larvae, Pupa workers and winged reproductive.  Once established they can damage a home’s structure this also includes new construction. Not surprisingly a satellite colony can reach upwards of 10,000 to 20,000 workers.

The ants usually maintain a trail between parent and satellite colonies. These trails can be seen in grass because they will cut and keep trails clean but are most used after sunset and through the night and decreasing by morning. Parent colonies are usually found outside within 100 meters of a house in stumps or trees, decorative wood in the yard.


Workers can be small and same size for the first 2 to 4 years but the parent colony can cast caste multiple sizes from 6-13mm long and the largest being the winged queen reproductive at 18mm. They can be of black to reddish in color. Examination of a color may not be best way of identification but they are one of the largest ant species we have in the Northwest.

They undergo a complex metamorphosis stage starting with egg then larva, pupa and adult. The eggs, and larva are clear and white and the pupa are white.  First days of spring the queens emerge from their nest, mate then looses her wings and start a new colony. However this can happen through the summer months extending into fall. The queens primary function is to brood the first set of eggs until the workers can take over the primary function of gathering.


Determine if ants are present as a nesting site or foraging food from the home, some indications can be frass which is the saw dust from the burrowing in wood or by looking at the abdomen weather it is enlarged or carrying food back to a particular destination in or out of the structure. Then a plan can be determined to prevent or control the ants. Cultural controls could be used to reduce or remove access and food sources can be controlled by planting away from structure or pruning. Stacking wood away from the home’s exterior, garden hoses and electrical lines can be a highway to the structure. Material control is often the best way to defend the home after some of these measures are implemented.