[Wrenchforhire]

I have made my swarm boxes, have a couple of locations selected, but when I looked at the old brood comb I have, its still got a lot of food in it.

One guy on youtube says that the new swarm would reject the box because of that.

Any suggestions?

 

[Hoot Owl Lane Bees]

try it and find out.
I use them in my swarm traps.

 

[Fivej]

I doubt that they would reject an otherwise suitable potential hive box because it has stores in the comb. However, you are inviting other critters because of the stores. Mice, wasps, hive beetles, wax worms, etc. You can still use it, but you will have to keep an eye on it to make sure other things don't move in. J