> Allen posted a comment about Medhat's formic acid method.
 > How is it different from the method posted by Allen on his site?

Medhat reads BEE-L, so he may add to this or correct me if I am off. My
information may not be the latest, but I think so.

There is no real difference, but lately, for double brood chamber hives
in fall, Medhat has been recommending two Dri-loc 50s placed on either
side of the top box, 1/3 of the way from the back.  I think the placement
is to minimize brood damage. Placing pads directly over brood will
definitely kill brood, but in fall, usually the brood is in a few frames on
centre, so side placement protects the brood.

I have to say that this application does drop varroa -- and fast. However,
the treatment has to be repeated a number of times for either tracheal
mites or for varroa, and the hives should be monitored to verify results.

Anywhere from 3 to 6 applications may be necessary although even one
treatment very is helpful.  Although generally a repetition every five 
to seven
days is recommended, that is basically the shortest wait that makes sense.
Longer or random periods between treatments work just about as well IMO,
but since the weather window for treatment is sometimes short, it is
important to know the earliest that one should repeat the application..

Basically, each formic hit kills X% of the mites in the hive at the time 
and
mostly gets phoretic varroa mites, which may be only 30% or less of the
total varroa load, although some mites in capped brood are affected.

These flash treatments release most of their load each time within 24 hours
of pads being applied, then we wait a few days for more mites to emerge
from cells and be exposed, then apply again.   Because each application 
only
lasts a day (if we ignore the effect on sealed brood which is variable and
unreliable) multiple applications are required.

Tracheal is relatively difficult to detect and quantify, so many 
beekeepers just use
several treatments when convenient since they know formic helps with 
varroa, and
weakens or kills any varroa that manage to survive the Apivar 
application, and
does not seem to harm the bees much if done properly.

This should reduce the likelihood of Apivar resistance developing and at 
the same
time reduces tracheal to safe levels for wintering.

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