Hive A had 17 - 19 mites on the board. When I removed the boards, I scraped off some Vaseline and (likely) mites. So, I estimated the number of mites that might have been in the ninth of the board to be 3 instead of the 1 that I counted. Hence, I'm going to go with the higher number.
Hive B had 33 mites on the board. One reference that I recall said that greater than 40 mite (in one day, mind you) was another indication for treatment. I'm still below that number, at least. In any event, I continue with the mites per 1,000 bees per day calculations below.
On 6/16/2013, Hive A had a population of about 9,375 bees (7.5 frames full of bees x 1,250 bees per full frame). On the same date, Hive B had a population of about 12,500 bees (10 frames full of bees x 1,250 bees per full frame). Again, we are going to say that this is over 4 days of collection.
- Hive A: 1 mite per 9,375 bees per 4 days = 1/(9,375 x 4) = 0.03 mites per 1,000 bees per day.
- Hive B: 10 mites per 12.5k bees per 4 days = (1/12,500 x 4) = 0.2 mites per 1,000 bees per day.
Even if the boards were only in for one day--and thus the mite numbers would be 0.12 and 0.8 mites per thousand bees per day--there would not be a clear indication to treat.
After this mite count, I did not get to a mite count for over a month. I did an about 2.5-day mite count that ended on 8/3/2013. There were significantly more mites, but there were also significantly more bees. I'm hoping to do an inspection over the weekend of 8/3/2013 so that I can get a good estimate of numbers of bees.