In my experience, yes. After a day with no foragers returning, younger bees turn to the task to bring resources to the colony. As they don't return, younger and younger bees are tasked to leave the colony. After a period of time the population of the colony is minimized and it is at this point that the funnel can be removed and the now stronger colony, which you have made queenright, outside the tree/structure can rob out the parent colony. Some say the old queen may eventually leave through the funnel but not in my experience. I think she perishes when the original colony is robbed out. You don't get any or the genetics from this feral colony except through the drones that you'll capture as well.
Good luck,
Pete0
Bena, VA