> The bottom line is that if a colony starts with less than 25 total mites in
> spring, and experiences less than a 500-mite immigration over the course of
> the season, it would by alcohol wash assessment erroneously appear to be
> "resistant," although the true reason was that it simply didn't start with
> enough mites to determine whether it was truly resistant or not.
>
> Charlie has questioned the degree to which immigration is related to the
> fall mite spike.  My revised modeling suggests that part of the spike that
> I'm seeing is due to the low starting mite population, but it would still
> take a lot of immigration in my operation to obtain the high spikes that I
> observed.
>

I am right with you on this. I know i have an issue with the sudden mite
buildup from almost none all the way through to August to several hundreds
after major robbing or immigration in September/October. I count mites from
a sticky board after every one of my OA vapor treatments, so I get most all
the mites with the treatment,. I got about half five days later and less
than that in another five days, which means emerging mites are the ones
being killed in the next two treatments.

If I did an alcohol wash instead of counting the actual mites being killed
by the OA I would have had one or none over the entire year.and even with
200 live mites in the hive in October, they also might not have registered
in the alcohol wash even though I had a rapid mite buildup in the fall.

I do not see how the buildup could have come from only a few mites in
August naturally building up to hundreds a month later. But it is easily
explained from either robbing or immigration. Also, a rapid collapse can
only be adequately explained from the virus brought in by either the
robbers or emigrants. The bees are coming from a collapsed colony and are
loaded mites carrying what killed the collapsed hive. So are the bees. They
can also transmit the virus.That is something that is often forgotten. So
it would not take as many mites and bees to lead to a rapid collapse if
they were all virulent.

That certainly would explain why I still had Varroa problems several years
ago when I only treated with MAQS in August. The first year was not good
but I got through with half my hives (2 left) and the others definitely
died from Varroa. The next year it was MAQS again in August, but this time
in Late September I saw BPV and definite Parasitic Mite Syndrome bees on my
tell carpet I have in front of my hives. I have recounted the story, but I
just got an OA vaporizer and it got my hives (that actually got the OA
vapor) through the winter. It actually cleaned up the BPV/PMS hive and it
is still thriving this March- 1 1/2 years later- in the still cold Maine
winter.

So, back to your observations. In each case when I had Varroa issues, I had
nearly no mites through and after my August treatments. So i also would
have appeared to have resistant bees that did not even need the MAQS or
last year's OAV treatments. But the September influx from wherever changed
all that and had I not treated again in October (and November), I doubt if
I would have had any bees after this hard winter.

My guess is that if you have good neighbors, all is well and things work
just like the book. If you do not, then you have to write a new book, so I
treat with OA Vapor once in spring, once if I split hives. 3x5 in August
and October and once in November. Why so many times? Neighbors.

Bill Truesdell
Bath, Maine

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