Or you could do what I do, never touch them.
Its possible though that if you start and stop playing a lot, they may multiply without your action, and may cause the game undue strain - 3-10 of them might lag themselves, but 40 of them might cause the game to take an hour to load into, and 20 more might crash the game on load
100 of them might still only lag themselves. - who really knows, honestly, I find it just best to keep them in check after learning they duplicate. "better safe, than sorry"