Timothy C. Eisele wrote:

>Second year: Make splits from overwintered hives, install new queens.
>All hives do well, with the overwintered parent colonies becoming very
>strong.  But, early in the winter the strong parent colonies die,
>leaving only the ones made from splits.
>
The statement about the strong colonies is the tipoff that varroa control
is the key to this situation.  The strongest colonies typically raise the
most drones and thereby grow the mite population most rapidly.  You need a
method for keeping the varroa population down during the whole summer
and especially as you head into September.  Bob Harrison just mentioned that
migratory guys use formic 3 times per year.  Alden Marshall pulls drone brood
all season.  I believe powdered sugar can work if applied often enough.
Whatever method you use, you have to verify that you have the mite
levels low enough.  Any bees with deformed wings, for example, suggest
that the mite level is getting too high.

I live in New Hampshire.  Given the bee-mite population dynamics, if a
colony has a serious mite problem on August 20, it is very difficult to
get ahead of the problem and have the colony survive the winter.

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