Strange Oxalic acid treatment results

[tjc1]

I just treated my two hives, both new packages this spring.
'Green' hive developed to expected size. Mite drop count on Sept 29 was 32 per day
'Purple' hive developed into a much bigger hive population. Mite count of 80 per day on same date.

Before treatment, both bottom boards showed a LOT of dead mites (boards had not been removed since 10/20)

24 hours after OA treatment I inspected bottom boards to find:
'Green' hive - NO dead mites, not one
'Purple' hive - over 1000 dead mites

How can this be? During both treatments I saw vapor coming out the top entrance, and the vaporizer was empty afterwards.

[GSF]

If this was me I'd be second guessing as to whether or not I treated one hive twice. Sometimes it takes 2 or 3 days for the mite drop to show up strong.

[tjc1]

I hear ya GSF,    but I definitely did them both, one after another. checking and cleaning the bottom boards before replacing them with the fume board. One other interesting point is that the hive with no mites dropped is also an aggressively hygienic hive - the bees were constantly out front grooming each other...