Hi All,

A week or so ago I mentioned that when I'd previously checked  for mites in
the drone frames as I split my strong hives in late March/early April that
I often find nearly no mites, despite that fact that from alcohol washes I
know that there are plenty of mites in the hives.  I promised on the last
post to confirm again.

We are currently splitting colonies about to swarm, each with plenty of
sealed worker brood, and one of my drone trap frames.  Mite washes of these
hives are typically runing in the 3-10 mites/300 bees level, which based
upon my modeling, indicates total mite loads in the 1000-3000 range.
Yesterday, beekeeper Konrad Thaler and I used cappings forks to inspect
drone pupae in about 6 trap frames (each from a different hive), and today
I went through 8 more.  On each frame we inspected about 200 pupae, and
typically found 0-2 mites.  Our estimate from the sampling was that there
would be at most maybe 10 mites typically trapped in each of the drone
frames (maybe even 20 accounting for those that we overlooked).  This makes
me wonder how effective drone brood trap frames are when colonies are in
swarming condition (as these typically were).

In these colonies the drone brood accounted for roughly 1/7th of the total
brood area, with a limited amount of additional drone cells elsewhere.
Going back to Boot's studies, in my hives at this time of year, roughly 75%
of the mites in the hive would be in the brood; half of them in drone brood
 (accounting for the larger size of drone cells),  So if there were 1000
total mites in the hive, I'd expect 750 to be in the brood, with around 375
in the drone brood.

The above number does not jibe at all with the numbers of mites that I'm
seeing in my drone trap frames.  So either the mites have evolved since
Boot's time and no longer have as strong a "preference" for drone brood
(this was recently suggested for the mites in South Africa), or one of my
other assumptions was wrong.  I guess that I need to pull out the scope and
start measuring and dissecting worker and drone brood in order to see
what's up.

-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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