On how long must Apistan be out of a colony before the start of the
honeyflow, I have heard various answers ranging from "pull strips when you
put on the supers" to "28 days".   The Apistan  label does not specify a
waiting interval; only that the strips must be out before honey supers go on.
  Personally, I time my Spring treatment so the strips are pulled about 3
weeks before the supers go on.
 
The 28 day waiting interval comes from Dr. Collison's "Spring Disease
Management" quiz in the March "Bee Culture".  Personally, I would like to see
the reference he used for the 28 days.
 
As for what is the actual minimum length waiting interval, to calculate it
would require knowledge of strip dose rates, Apistan decay, transport, and
dilution factors, as well as the maximum acceptable concentration in
commercial honey.   Let's just say it would be a mess and probably have a
large margin for error.   However, the nature of the Apistan product (a
contact miticide that is not terribly volitile) makes significant transport
to the supers difficult, and almost impossible if the strips are not present
in the hives along with the supers.
 
Now for the second question:  Do old, abraded Apistan stips work acceptably?
 The answer given at various Maryland State Beekeeper's Association meetings
is a flat "No".   Use new strips each time.
 
W. G. Miller
Gaithersburg, MD