Oxalic acid DID NOT KILL ANY OF MY HONEY BEES OR QUEENS! Formic Pro formic acid kills only honey bees including queens, NOT VARROA MITES! I currently have 99 colonies and they are NOT dying from varroasis at this time. Depending on what kind of winter and how long it last will determine how many colonies I have next May. I have doubled my colonies every year after the Foley fiasco. Breeding my own queens has proven to be the best option and by far MUCH CHEAPER!