Honestly, that's all I can figure. I've done 7 treatments of OAV, every 5 days since Sept 13. I'm counting the mite drops every day, and after every treatment the counts get higher and higher. I've tallied the 5 day mite counts between each treatment, and it has increased with every treatment. Today was 2 days after the 7th treatment and I had 721 dead mites on the bottom board. That's the second highest count on this hive since I started treating, and exceeds the previous second highest count of 552 which happened yesterday! I've now killed over 8600 mites on this one hive. The more I pump oxalic acid vapor into the hive, the more mites I get. I conclude, therefore, that mites are spontaneously generated, and are made from Oxalic Acid Vapor.