I had disasterous results with formic acid similar to yours. I think the
problems went far beyond the packaging leaking and that the delivery rate was
high enough to kill or damage the queens. I think they were pretty closed
mouthed about it and they probably lost a customer.  Looking back I remember
"Big Johnson" down in the Carolinas having the same problem.  If beekeeping
mandates the use of checkmite then there will be a large bonfire here and a
lot of 16x20 garden planters. Or I will be buying packages from the folks who
use checkmite.  I just don't want to use the stuff.
  I have just gone through a major wave of splits and requeening here and
will probably miss a good percentage of this years crop.
  Last fall a bear was sighted within 1/8 mile of my hives but then not seen
again.
Still a drought here in the Northeast USA and the pollen count can be
measured in inches. Cool and windy, not much flying going on today.
   I have a roll of 1/8" hardware cloth sitting in my front hall. Another
project