What kind of temperatures really endanger capped brood if a hive is light on bees to cover the frames?
This spring I did some early splits as soon as I saw drones. 4-5 frames each and lots of bees (for the spring). I checker boarded them in 10 frame deeps. We had several 32 deg nights and all was fine. I kept an eye on the entrances for days and no larva was carried out. These hives exploded as the flow started.
I don’t know the danger temp but I hope this helps.
While I cannot provide a scientific answer I can state that I have inadvertently pulled some frames with capped brood ( no cover bees -- blown off ) and placed them in an unheated garage. Overnight temps droped to about 65F. Bees were hatching and flying 2-3 days later.
I hate when that happens -- Fuzzy