I cleaned and replaced bottom boards, brood chambers, and put new Killion bottom boards on all my colonies just over 5 weeks ago. In the interests of understanding mite dynamics in a tolerant colony, I pulled a bottom board today and counted the number of mites. On the entire bottom board, I found 15 mites. There were also 12 dead bees and about a half cup of wax debris. This was going over it with a fine tooth comb and a large magnifying lens to ensure I did not miss any. In one 6X6 area right beneath the cluster, there were 3 dead mites. The cluster at 32 degrees is just a tad smaller than a soccer ball. So somebody analyze what it means when you find 15 mites on the bottom board after @35 days. Does anyone think this colony is in trouble? Would it help if I said that they have been totally untreated since 2005?