In this scene Macbeth Mentions “The shard-borne beetle…”, he is referring to the upcoming events and how awful they will be. When he mentions the beetle the camera will focus on a bug on the wall. Macbeth will still be in the shot, the focus change will last less than a second. The beetle will be there as a confirmation to Macbeth’s fears, even though he wont notice the bug.
7800macbeth 