They move 4 spaces, so figure that in before Bugs push. It's used to break blocks in Bug's path. They generally chase Bugs all around the maze. With rare exception, they can only climb up. They cannot climb down ladders, pipes, or passageways.
Bugs is on.
If you stay still, the dark Hector will climb up the ladder. Normally, these enemies never climb down ladders. To this date, I have no idea if the Foghorn in level 13 is dark or not. IF you know how. For reference the very top and very bottom of the levels are always an odd number of squares from the bottom of the level, so they always go up at these two points.