Is this also accurate for a hive with a virgin queen? I have 3 hives that I "think" are queenless (no eggs or open brood), but they all had a single queen cells that are now empty, but some look like they were chewed open by the workers (larvae used to make emergency QC of unknown age or quality).Michael Palmer has a video on how to check for queenlessness in a hive using a caged queen. Since you have a caged queen, you can use it to check your hive.
I'm picking up just one queen tonight from a local guy. Plan to try the Michael Palmer test tomorrow to determine which hive to put her in.