I promised Squarepeg I would post this, although I now don't know if there is any educational value to the story.
I have 4 hives: a brand new nuc grown into 3 boxes, an overwintered locally bred Italian mutt, my captured "grapefruit swarm" from last fall, and my Carniolans, now entering their 3rd year. In year 1, the Carnis were the only hive to survive, and they were booming all last year, and this one as well. (They brood up starting in late January, and by Valentines day are ready to go... this might sound awful, but down here, we have mahonia, dandelion and some fruit trees blooming then... they were right on schedule for my area). In year 2 I had 3/3 survivors.
I'm always trying to learn new skills and knew I needed to be mite-washing. So, I got some empty peanut butter jars and some rubbing alcohol and decided to roll some bees last week. And was promptly shocked.
I only had two jars for samples so I sampled the two oldest: the Italian mutts and the Carnis. The Italians rolled a 3.5. The Carnis rolled a shocking 50. Panic set in and I spent the next few days trying to figure what to do next. (Before a lot of questions about technique come in, I have a science background so my method and statistics are standard. The Italians had 11 mites for a rounded 1/2 cup. The Carnis were not exactly countable since mites covered the bottom of the jar, but I estimated 150 based on a quadrant I counted. It might have been more).
I won't go into the research and decisions and panic and grief which followed. I realized that my sample from the Carni hive was at the tail-end of the nest and was nearly 100% drones. That gave me some false hope. I sampled again today from the middle of the nest and got a 30 (which is better than 50, I guess). I was hoping for a miraculous 5 or something. On going through the hive I can tell it is depopulating. I don't see any evidence of virus (no DWV or K-wing, or drunken zombie-bees). The hive population is about 50% drones. I started triage with an eye towards ending its life responsibly. (I removed 9 combs of honey and nectar today for freezing and giving to the other hives once they are pest free. I'll start freezing brood and dumping bees in the soapy water on Friday, unless someone here shows me a better option).
[In hindsight, I can tell the carnis were probably struggling last year as well, but they pulled through and did well this spring. they appeared weak last fall, but exploded in January].
I sampled the grapefruit swarm today (named for the puny size it had when I got it), and it rolled a legitimate 0. I washed the bees 4 times trying to get a single mite off of them. They really are a terrific colony. (I may have to rename them since they are now the size of a couple of cases of grapefruits).
I don't know if there is any moral to the story, or an alternative to my planned euthanasia. Here's what I learned.
* Perform mite-washes. The results might surprise, and more data can't hurt and may be a definite benefit.
* My longest lived, very full hive was not my healthiest. I let its reputation, history, and population lull me into thinking it was fine
* Sample from the middle of the nest (although infested drones imply infested workers). I'm not sure how important this really is: 50 or 30, either one is in "OMG" territory.
* For my hives, anyway, there is a direct correlation between mite score and activity (not total population, but growth rate). The 0 hive I would give an A+ (growing so fast I can't keep up), the 3.5 hive is growing moderately (2 or 3 combs a week during a flow... a B), and the 50 hive was fairly stagnant when I tested it, but is now clearly shrinking in population (had abandoned 3 combs at the end of the honey area, F).
* Sometimes your favorite hive is the one which has to go....