My experience is that a queenless swarm, for whatever reason, returns to the colony in short order. 

Queens not quite ready to leave often fly a short distance and end up returning, and if the hive has a screen bottom, you can sometimes find her under the screen with a cluster of bees. If you miss that bees and the queen are underneath, they start building comb. Not quite sure why they go underneath screen boards, but I have recovered a few queens of my own, and when I get a call about bees under a screen, there is almost always a queen with them.  

I often think about a prime swarm that went about 500 meters from my apiary and bivouacked in a neighbor's apple tree. They alerted me, and I checked on the swarm, reassuring the neighbor the bees were not harmful and would soon leave, but they stayed. They formed a tight cluster, which usually indicates they have a queen, and it appeared they were sending out scouts. Later that day, hours later, the cluster broke and flew back into my apiary and returned to the box they swarmed from. It just seemed odd that they would take so long to return. 

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