That very small DARG study by Richard Ball (ex head of the inspectors south of the border) is compatible with the bee gym working as advertised. However one hive with a bee gym and one control isn't nearly enough.
The Apidictor listens in (and seems to work) whereas the Varroa control thing blasts them with sound. The Apidictor filters out the sound of several thousand young bees getting ready to fly off with the swarm. Swarms have many young bees in them and this preparation of young bees to fly is characteristic of colonies approaching swarming.
Bookmarks