So, I got to the point where I was frequently seeing mites on live bees, maybe 3-5 per hive that I noticed. I decided to treat using oxalic acid dribble. I mixed up a couple quarts, using 1:1 syrup to 1.4-1.5oz of OA crystals. I treated (5ml/cc per seam of bees) and saw a little bit of mite drop. I scratched my head because it seems like there should have been more dropped due to the higher infestation. Oh well. But then it hit me: in a previous thread, someone mentioned that heat erases the effectiveness of the acid. Ahhh! I used hot water to dissolve the sugar in the syrup, and then added my OA crytals immediately afterward. Was this my problem? I think so. What do you think? I worked all 20 of my hives today and saw about 10-20 mites on live bees in each hive!!!! The OA definitely did not work, I suppose due to my ignorant blunder with the hot water. So can I retreat my hives? either with oxalic or formic? Will it harm the bees? All input is welcome. Thanks in advance!