> My sticky board daily mite drop averages for the year have been:
 > ...Aug 23        27.0

 > I vaporised 2 gm of oxalic into the hives on Sept 1 and inserted 4 
sticky boards.
 > The next day I counted an average 1 day drop of 750 mites.

An excellent report!

I like evaporated oxalic and I like sticky boards and it is clear that 
you are
getting results even though there are likely still about three or four
frames with brood.

At this time of year, the lifespan of an adult mite is likely more than the
100 days that i use in spring and later in fall, but just supposing we use
that number, it gives us 100 X the daily drop or 2700 mites per
hive -- assuming your number was the average drop per hive.

Again, estimating, that means you got roughly 1/4 of the mites.    That is
not bad, and oxalic evaporation can be repeated multiple times without
reported damage to the bees.

You report the first day kill as 750, but we would expect higher drops to
continue for a week after treatment, so we'll be interested how that goes.

Assuming, again, that half the mites are in the brood, then after the
brood reduces, your kill rate will climb to 1/3 and 1/2. It add to be 1/3
or more already over the coming days.

This is the critical time for winter bee development, so knocking down 1/4
of the mites and weakening others is helpful.

Again modelling, 3/4 (surviving) x 3/4 x 3/4 = 27/64 = 43% kill with
three treatments.

If you are getting 1/3 each time, then
2/3 (surviving) x 2/3 x 2/3 = 8/9 = 89% kill!

I'd recommend every five to seven days to get the best results by hitting
each bunch of newly emerged mites.

Of course this is all theory.

Please keep us informed.

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