Two dead hives

[1hivegoin]

Was 55 degrees and I saw no bees flying from my two hives.  Looked inside and saw lots of honey and pollen and the bottom board (screened) was packed with dead bees.  I had ut an entrance reducer on last fall, perhaps they got all clogged up in the opening?  Deconstructed hives and froze honey for this spring when I hive new colonies.  Any reasons why my bees would die while having a lot of food?  Hives seemed fine at the end of summer.  The bees didn't leave the hive, they all died inside...

[Finski]

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Tracheal mite has habit to kill with that style.

http://www.entnemdept.ufl.edu/creatures/misc/bees/tracheal_mite.htm