Chris,
I only have three hives and run into this problem all the time. I
wrap the unused strips in Saran Wrap, then in a plastic bag. Mark
the bag and put it in the freezer so it does not get mistaken for
something else. It should keep for a year or more. My guess is a
lot more, but I cannot prove it so err on the short side.
Use Saran Wrap and not other brands of plastic wrap since it will
not breath like other wraps.
The colder you keep pesticides, the longer they last, since their
half live is temperature dependent.
Bill T
Bath, ME

 How does one best keep opened packs of Apistan?
> Chris Slade