I have two hives I want to combine. I understand about finding and killing the weak queen, and placing a sheet of newspaper between the hives with two slits cut into it for the bees to eat through and get aquainted. What I'm not clear on is what time of day should combining be done. Do I wait until the field bees are back at twilight before I combine or should I be concerned about the field bees at all? Thanks for your help.