>I'm just a backyard beekeeper.  Ok, two back yards.

Me, too.  And I need a third, too.  I completely lost three colonies to 
robbing in the last month, so I've also got similar problems.

>I'm not looking to clean out the mite.  

Me neither, at least not completely.

Perhaps I should explain what I do and maybe a little of how I got there.  
This is only my third year with a significant number (10+) of my own 
hives.  (I've worked for other beekeepers full-time and kept just a few 
bees on the side previously.)  In 2004 I put a lot of time and work into 
treating hives with indications of moderate to high mite numbers with 
sucrocide.  I wasn't impressed with the sucrocide, but I think my cautious 
efforts, combining, and a healthy dose of good fortune were what brought me 
through that winter without losing a single one of my 39 hives.  I was glad 
not to have lost any hives, but I figured I had probably been more cautious 
than I needed to be.  Maybe I could have brought more colonies through if I 
hadn't combined them in the fall.  Maybe I could have spared myself the 
time and mess of some of those sucrocide applications.  So I set out to 
test my thresholds in 2005.  Mite loads were also a lot higher in 2005.  I 
took natural mite drop tests (again) on all my hives.  I basically let 
everything go without treatment.  I lost 40-45% of 50+ hives.  Some of 
those were probably late splits that never built up well enough, hives I 
should have combined.  Of the normal strength colonies, I didn't lose a 
single hive with fewer than 55 mites per 24 hours in early September, here 
in the North Carolina foothills, nor did I notice any disadvantage the 
following year.  (I lost almost every hive with counts above 55.)  
Meanwhile, I've only bred from colonies that first caught my attention for 
vigor and productiveness and then survived without any treatment.  I've 
replaced every queen that I felt the need to treat.

So what I'm suggesting is that mite resistance might manifest itself in one 
of at least two ways: (1) bees might keep mite numbers down or (2) bees 
might withstand a given mite level better.  The practical advantage of 
breeding for #1 is that I can survey mite levels, disqualify some hives for 
breeding purposes, but still carry them over (by treating) to the following 
year when I can requeen them.  In other words, I can select for mite 
resistance without having to lose so many colonies.

Incidentally, 90% of my 50+ hives have might levels well below my supposed 
55 threshold this fall.  I drone trapped on about 20% this year, but that 
leaves 70% that are presumably good to go having done nothing special.  
Although most other beekeepers don't test as extensively as I do, if at 
all, my rough impression is that most other hives in the area are about 
like mine this year.

Eric

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