I have five hives in the yard near my house. I live in MI There was a normal amount of dead bees (1cup or so) at the entrances when the really cold weather hit in the end of Nov. last week we had a warm snap, 2 days of 50-60 degrees, all of the hives were active making cleansing flights. In the past few days i have noticed a LOT of dead bees at the entraces and even blocking the entrances, Two of the hives had Quite large amounts, (like 1/4-1/2 gallon volume wise). i have no idea what is going on, they seem very healthy and vigerious going into winter, mite counts were ver low, every thing looked good and they still have tons of honey left. I have no idea what is going on, and i'm getting very worried!! if any one has any ideas please let me know.