About a week ago, on Monday 8/22, I went into my hives and installed what beekeepers call MAQS--Mite-Away Quick Strips. These are one of the least invasive, least chemically-onerous ways of treating bees for mites. I hadn't seen a lot of mites on the drop trays, but it's better to treat in the late summer rather against the possibility of a huge infestation setting in during the fall.
As prescribed, I took out the strips yesterday and found tons of dead mites under my big hive, but very few under the smaller ones. Most of that may just be the difference in size (the big hive is currently 5 boxes tall, while the smaller ones are only 2). But it may also be that the new queens I got from my mentor for the smaller hives are of a more "hygienic" genetic strain. Some bees are just better about cleaning themselves and each other, and they rid the hive of mites more effectively because of that. On the other hand, if they were better about cleaning, I'd be seeing more mites on the trays. So who knows?
Either way, I'm happy with what I've found, and I'm really happy with these new queens: the culture of those hives has changed completely. We cracked open the hives yesterday and they barely noticed. They're sweet, now.
The plan for this fall is to open up the big hive, kill the queen (who produced those aggressive new queens), and divide the boxes of brood and honey between the two small hives, thus making two big strong healthy hives with young queens going into the winter.
Beekeeping! Never dull!