>>flee the area
For bedbugs in hotels, it is now standard to kill them with heat. Since they tend to flee, though, you need to first heat up all adjacent rooms above, next to, below and diagonally, so they flee into the target room. Then you crank the heat in the target room until they're dead. I guess exterior walls are okay b/c once they're out of the building the die of other things? Not totally sure.
Anyway, point being that you want to make sure you plan for where they flee to