Carpenter ants.
DE or Diatomaceous Earth. You can get the food grade, non toxic, they have an accordion like thing on amazon too (pest pistol) to spread it with (definitely wear a mask, it's not poison but you don't want to inhale it).
DE is a drying agent, basically they get coated with the dust and will wither and die. Go along the baseboards and the base of the foundation if you can.
This crap works on spiders, millipedes, and centipedes too.
Unfortunately it does diddly squat to asian stinkbugs. 
In florida we made a poison for the pharoh ants we had and it worked for a little while.
worked wonders on the roaches though. i made a batch and put it in plastic because their favorite thing was to come in under the doors or windows - though the windows were pretty well covered by anoles and toads, some still got through. Anyway, they would head straight for synthetic stuff - they seemed to like styrofoam, silicone (they ate the silicone covering on my water bottle) and plastic wrapped stuff. So I made baits with wax paper and plastic and put them near the doors (and yes, I never thought of changing the door sweep). They would come in, eat through the plastic and then go out. In a few days they started showing up dead.
Never saw any dead ants, just a reduction in activity and a few days absence after a while. Then they were back. Followed their path outside and sprayed regularly with this foul smelling all natural stuff and same thing - gone for a few days, then back. Can't remember what finally worked, just that it was a less toxic formula that had to be reapplied if you looked at it wrong. Haven't seen anything like it here, that's why the research. Apparently the U.S. is a lot better at some kinds of toxic.
Since we are on the second and third floors I would not be able to do the base of the foundation without letting our neighbors know. Would that stuff harm dogs. There is a little one I don't care about, but there is also a very friendly aging german shepherd named Larry who eats our steak bones. Wouldn't want to harm him.
What about the window sills? Could they be coming in there? There is also a chance they are coming in from the roof. The sleaze was repairing the gutters, which were attached to the roof via the wood he replaced. Very strange arrangement. The building is from the 1800s. I also have a hole in my wall. My bedroom is under the back part of the roof, and the hole is about 3/4 down from the top of the roof, which might leak. I could put some in there, but I don't want to waste what i have until i get a source for more. Haven't seen that here either.
