After inspecting the home from top to bottom, I found frass from the carpenter ants in the basement. Frass is the remnants of excavated wood that carpenter ants removed from their nest.
Turns out there was a plumbing leak that moistened the sub flooring, header boards and joists in the basement. Since carpenter ants prefer to nest in moisture damaged wood, they set up shop here.
Using a residual dust, I treated up into this wood in the basement.
Behind the insulation to reach the sill plate and header boards....
And behind the plumbing pipe chases in the basement and the pipe chases under the kitchen and bathroom sinks.
Just to be thorough, I treated the garage door jambs and around the door and window frames around the exterior.
Once ants come in contact with the residual, they'll carry it back to their colony and share it with the other ants and the queen either through grooming or feeding one another.
Soon the entire colony is eliminated. I advised the homeowner to repair the leak to avoid future pest problems, to which he agreed.
Just recently, I performed a carpenter ant treatment for a homeowner in Holmdel, NJ.