Soon it will be time to treat with Oxalic Acid. I recommend doing this treatment.
This treatment is done when no brood in the hive. With no brood in the hive, all the mites are on the exterior of the bees. These phoretic mites are riding on the adult bees. The mites are very vulnerable to Oxalic Acid at this time. The mites are not hiding in the capped brood any longer. So this external treatment is perfect for the external mites.
Oxalic Acid is Wood Bleach. Beekeepers use the powdered kind of Wood Bleach. Wood Bleach (Oxalic Acid) can be applied with the dribble method or with vaporizer method.
The best time to use Oxalic Acid is when there is no brood in the colony, which usually is around the third week of October. Italian honey bees can be tough to treat with Oxalic Acid, because they can run brood into November. But I would still treat any way.
Treating with Oxalic Acid depends on the temperature at the time of treatment.
With the dribble method, the temperature needs to be at 40 degrees at the time of application. That is four zero, 40 degrees. Not 45 degrees, or other temps in the forties. FORTY DEGREES. The temperature can rise later after the treatment without any problems. At the time of treatment it should be 40 degrees.
The reason for me being persnickety on the temperature is this, at 40 degrees the bees will be in a tight cluster. The bees will be in a tight mass and can easily be treated with a syringe filled with the Oxalic Acid solution. As the temperature rises into the upper forties, the cluster becomes looser and the bees will start moving around the hive, making the dribble method less effective.
The vaporizer on the other hand is much more forgiving. Because the vapor is everywhere in the hive, a treatment temperature range between 40 and 48 degrees works fine. Even if the cluster of bees loosens up and the bees are moving around, they will still get vaped. Don't treat if it is too warm, if it is in the fifties for temperature, that is too warm.
Here are a couple videos I made about treating with Oxalic Acid.