Only an occasional water bug, but no ants!!!

I live in Sampson County, North Carolina, and from time to time we do have little field mice decide they wish to reside with us. Although I've had to get the trap out the few times, ugh, they always seem to be in the room that I have forgotten to plug in the repeller after using the outlet for something else. It's really hard to say if they work. That said, the only pest we really see in the house is an occasional water bug. One thing that is extremely unexpected, the ants (black- big and small, but especially happy not to see red ones!) have remained outside!