Re: Which bees leave in a swarm? Field bees? Hosue bees? Nurse bees?
It can have all ages of bees from ten days old and up, as at ten days the bees have their first orientation flight and are ready for wax drawing and nectar storage duties. That means they also have field aged bees as well as they'll need foraging staff when they find the new home. And, don't be surprised a bit if there's some drones in there, especially if the swarm queen is a virgin. I say this because hives with virgins tend to draw drones in from other hives. This is how I see the makeup of swarms anyways.
20+ years, raise my own queens, feed when needed, I treat but have not perfected varroa management yet.