> yet simply cutting out whatever drone brood is there
> > on regular inspections appears to help.
>
> >The problem was that cutting out drone cells assured
> that the bees would both replace the cut-out comb area
> with drone comb again, and also convert worker cells
> to drone cells as a short-term reaction to the sudden
> lack of drone brood.


I'm sorry for being unclear, Jim!  I only cut drone cells out of the drone
trap frames the Brian and I were speaking of.  We do indeed want the bees to
draw replacement drone comb in them.  I find that by giving them a place to
do so, they don't build it elsewhere.  Seeley, in the study that you cited,
found the same to be true.


> >but feeding drone brood through the capping
> stage is "expensive" in both resources and labor.


Yes it is.  But as Seeley concluded:

"Certainly, by steadily killing the drone
brood, a beekeeper will reduce the stresses
caused by mites and he will reduce the cost
of fueling the drones' mating flights. But
will the steady removal of drone combs
filledwith capped brood erase fully the neg-
ative effect of drone comb on a colony's
honey yield? The answer to this question
awaits further research."

There is ample evidence that the presence of varroa at any level will
suppress honey production.  The question, therefore, is at whether the
benefit of a lower varroa level outweighs the cost of the extra drone
production.

An ancillary question that I have is just how critical is it to remove every
round of drone brood produced.  A large proportion of the mites in a colony
are apparently in the drone brood.  Even occasional removal of a frame of
drone brood may be enough to outweigh the increased mite reproduction when
drone trap frames are allowed to remain in the hive producing drones.

I found several colonies in my operation last summer that I had
inadvertently left drone trap frames in through the season, without removal,
other than twice in the spring.  Those colonies did not exhibit higher mite
levels than "control" colonies side by side.  Indeed, some of them had
extremely low mite levels, despite the presence of a drone frame!

>
> >Another approach to "interrupting the brood cycle" might be
> to treat with Oxalic acid in spring/summer, which would kill
> most of the open brood along with the varroa.
> Seems too draconian to me.


I have experimented several times treating colonies with a full oxalic
dribble three times at weekly intervals during the late summer.  Dr. Marion
Ellis has done so also.  Neither of us found it to be noticeably stressful
to the colonies.  Brood rearing continued, and the colonies recovered
nicely.  Note that this was on colonies that already had high mite
infestations, and were thereby already stressed.  Despite the multiple
oxalic acid treatments, the colonies bounced back.

I'm not saying that OA is not stressful to a colony--there is plenty of
evidence that it is.  However, there are times when it is far less stressful
than a high varroa load.

Most respectfully yours,
Randy Oliver

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