I’m sure my bee left their hive in the fall because of the Varroa mite, I will be treating this year, I had two hive that made it through winter but died off when we went through three weeks of rain. I should have feed them more. I already had one of my hive come back and I plan that more will follow.
RESPONSE: High varroa mite populations are apparently one of the reasons bees abscond (leave) their hive late in the fall. I say apparent because there is no experimentation to “prove” that assumption. Colonies do have a tough time in the spring and can perish when the weather takes a turn for the worst. Sorry you both of them. Better spring weather helps them recover.