we made it up into the mid-sixties today and i made the rounds to observe the entrances for pollen coming in.
homeyard - all good
outyard - all good
overflow yard - pollen coming in 2 out of 3 hives with no activity at all for the third hive.
a closer look revealed the reduced entrance was clogged with bees
an ear to the side of the hive and a couple of knocks revealed it had gone dead quiet. this hive had good pollen coming in the last time it got warm here and had strong cluster roar 3 days ago.
the population was decent for this time of year with at about 3 deep frames worth of bees. there was capped brood about 6" in diameter occupying 2 adjacent frames in contact with honey.
the screens over the notches on the front and back of my inner cover were completely propolized over. the bottom board had a solid layer of dead bees that was thicker toward the entrance.
i'm guessing the co2 levels became toxic and all the bees died at once.
i don't think i've ever been this bummed about losing a colony.
i have reduced my entrances more this year as a hedge against robbing and have had to clear dead bees from some of them here and there over the winter. i also had previously noted that i needed to replace that inner cover for another one with fresh screens but didn't get around to it.