> Just curious... when inspecting a hive, if you pull a frame and scratch
> off some drone brood to check for mites, what sort of numbers do you
> expect to see?
None. If I see more than the occasional one, I'd worry, especially at this
time of year, seeing as the prime varroa build-up period is ahead of us.
> In the process of inspecting, one inspector checked a lot of drone brood
> for mites... and as far as I know, he found none. Zero. Zilch. The one
> inspector says he expects to find one mite on each drone he checks... bad
> mite loads are 3-4 mites per capped cell.
> What do you think?
I think he must visit a lot of beekeepers with their varroa out of control.
Let's do the math.
Given that a 1% phoretic mite level, determined by alcohol wash, is the
current treatment threshold here in Alberta.
If a hive has 20,000 bees right now, then that 1% means 200 phoretic mites.
Many hives have fewer bees than that right now in Alberta.
If half of the total phoretic mites in the hive are in the drone brood, that
is 100 mites in brood.
(Not all brood is drone brood, so this is a significant over-estimation).
If there are 20 square inches of drone brood, (4" x 5") that is 18 per in^2,
so the total is 20 x 18= 360 drone cells.
At the 1% threshold -- 100 mites in drone brood -- one mite would be found
in every 3.6 cells -- if all these assumptions are correct.
In the real world, the frequency is considerably less.
Most of the hives I see don't have visible mites in the drone brood.
I can say I have seldom seen any in mine, and I am usually over the 1%, but
I'm not really looking.
I don't consider obvious numbers of mites in drone brood to be an accurate
indicator of anything except impending doom.
allen
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