To kill mites. Mixed half of the solution with 50/50 sugar to water, the other half was straight lemon juice concentrate. Applied with a fine mist spray nozzle.
The first hive I did - about 60 days ago - was a split where I took the queen away from a large successful hive along with 5 frames of nurse bees and capped brood. This hive was exhibiting the normal stress from a high mite infestation. The old queen worked for a few weeks and disappeared. The hive has recently requeened successfully with no sign of mites as of yesterday's inspection.
The queenless forager half was not treated. It successfully requeened naturally and in the process cleaned the hive out. The new queen is laying like a champ and there is just a little sign of mites. Next inspection I might apply the lemon juice if it appears the mite population is growing.
Then another hive was showing heavy signs of mite infestation including deformed wing virus. This was a great hive that produced 4+ supers of honey early summer and now nothing with a crashing bee population. I split the old queen off 11 days ago, with nurse bees and all the capped brood, but one frame with the freshest eggs, and treated heavily with lemon juice. There were mites everywhere. The other half I did not treat. Yesterday's inspection I treated the old queen again and also treated the queenless hive as there were mites all over and I decided there is not enough time left before winter sets to have the bees adapt. They have created quite a few queen cells on that one frame.
Then, one other hive - in this garden colony - was started from a split, from the first hive, before the mites took over, is cranking out the workers with no sign of mites.
This is my experiment to see if this lemon juice method works.