> ...If you have a hive with a lot of varroa/ virus at the fall, oxalic is 
> no miracle. If the winter bees have already been damaged in pupal stage by 
> mites they will not live long even when the mites are removed by oxalic... 
> if you have a lot of mites ( mote than 300) in end of July you must treat 
> with something to protect the developing winter bees for the hive to 
> survive. + use oxalic later.

The question is what to use in that event, especially when the hives are 
full of bees and some supers may still be on.

Take a look at http://www.reineschapleau.wd1.net/articles/flash.en.html.

I have not personally tried Jean-Pierre's methods, but they strike me as 
elegant.  His methods allow for easy, instant, and frequent, varroa 
monitoring by observing natural mite fall on the paper in the drawer below 
the screen, plus the means to do fast, minimally invasive formic application 
with no disturbance of the stack of boxes above the floor, again using the 
drawer.

Moreover, the quick observation feature allows for detecting the colonies 
that have a problem and treating only them on that round, while skipping the 
ones that show little drop.  A quick glance at the paper in each drawer 
should tell most beekeepers what they need to know about that particular 
hive.  Treatment, when required, is by squirting a measured dose of formic 
on the paper.  FWIW, I am not recommending treating with formic while supers 
are on, even in an emergency, but have heard of it being done, and cannot 
see any hazard to the crop from doing so, since formic is already a natural 
constituent of honey.

For formic, some beekeepers are using the Mite-Away(TM) method.   Although 
manageable at other times of year, Mite-Away treatment would be very awkward 
and difficult in the circumstances we are discussing here.  Additionally, 
that product is expensive, requires additional hive parts and has proven 
variable in success, particularly where the weather changes during the long 
treatment period and results in colony damage or incomplete treatment. 
Medhat was the original inventor of the Mite-Away technique, and I am not 
sure he still recommends it.  Maybe he will say.

On the other hand, the flash method takes place during the hours immediately 
following application, when weather (temperature) is more predictable.  With 
flash, repeated treatment may be required, but the job is simple and the 
timing is not critical if the goal is just to knock back varroa levels 
temporarily.

Formic also neutralizes tracheal as an added benefit.  The downside is that 
liquid formic is hazardous, and must be transported and handled 
appropriately.  Emergency equipment (a bucket of fresh clean water) must be 
kept constantly at hand.  Search the extensive discussions in the BEE-L 
archives about formic safety. (See tagline for URL).

The floors, as purchased direct from Chapleau are a little bit fancy and 
lightweight for heavy commercial migratory use, but a real bargain for those 
with less demanding service.  Many commercial beekeepers are building their 
own rugged, simplified, palletized versions.

allen 

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