Hello Peter & All,

>As this is most probably considered to be an un-expected event by many,

Is a surprise to me and not what was expected. Those beekeepers had control
problems with formic  last fall after California almond pollination. My
guess was a application problem then.

Now reports are surfacing of the same problem of low varroa kill with
formic. It is hard to put a finger on what is happening.

In Canada beekeepers used formic once and then used apistan in say fall.
These varroa are resistant to both Apistan & Checkmite so there is no backup
treatment.

It is too early to tell if these varroa are able to build resistance to
formic acid. I know of no test (as there is with apistan & checkmite) to
tell. Does the list?

Low kills with formic are not uncommon but most can be linked to the wrong
dosage. Low kills with Apilife var can also be had.
Most can be linked to waiting to late in fall to do the treatment and varroa
loads were over threshold.

The beekeepers referred to say was not the case this year.

I am only reporting the problem as told to me. I did not think varroa could
become resistant to formic acid.

Bob

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