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