Joel Govostes wrote -
 
> The ideal time to treat, as I understand it, is when there is little or no
> brood; then all the mites are gravitating to adult bees, instead of being
> hidden in capped brood cells.  SO, that means October, maybe into November
> around here, while the bees are still somewhat active."
 
Ted Fisher replied -
 
> This was my philosphy too, last year, before I lost most of my bees to Varroa.
>  We generally get a good fall flow in southeastern Michigan, and my hive
> population is *way* up after removing summer supers.  However, I learned (by
> the best teacher) that when the colony stops producing drones (basically right
> now) that the varroa mite then goes into the worker cells, the very workers
> which should be the ones to provide the winter cluster bees.  When these
> workers are decimated, there is no hope for the colony.
>
> Therefore, my present practice is to give up the fall flow in order to save
> the hive.  I try to put in the Apistan strips as soon as the summer supers are
> removed.
 
I'm glad that Ted Fisher wrote this because this is what I think too!
 
When brood rearing begins to diminish after the height of the season
- and there will be a lot of Varroa bred on the bees - there will be
less brood available per breeding mite.  The consequence of this is,
as I understand it,  is that each larvae has a far greater number of mites
parasitising it.  The consequence is a population of larvae - that one
would wish to mature to provide an overwintering population -
either failing to survive or being so seriously deformed as being
useless for any purposes and prone to other diseases.
 
I would suggest that treating bees as soon as the honey crop is
removed and then feeding to stimulate a healthy overwintering
population as the best strategy.  Although I don't use Apistan or
equivalent,  they do at least have the advantage of providing a very
quick knockdown of the majority of the population of mites,  so one
could feed only a few days after treatment in the knowledge that the
colony is likely to rear healthy young bees for the winter.
 
> Incidentally, I am harvesting my summer flow now, and am getting up
> to 160 lbs per colony (average=126 lbs) from new package colonies
> (single queen).  Ever since the mites killed off the feral bees, I
> have had record yields.  Is this the case elsewhere?
 
Apparently honey yields in Germany have risen,  once feral bees have
been infested,  and beekeepers have developed strategies for living
with Varroa.
 
Also,  and I don't know about beekeepers in the US,  but in the UK
there have certainly been quite a few beekeepers who practise
'let-alone'  beekeeping.  The 'let-alone'  beekeepers do not treat
their bees against Varroa (or anything else!) and provide a reservoir
of mites to infest other colonies whose owners take more care.  After
a year or two the 'let-alone'  beekeepers give up beekeeping or
decide to treat their bees - and the level of
reinfestation drops.
 
Best wishes
 
Joe Hemmens