Very few beekeepers seem to know about the Torpor state some bees can go into.
This is when the bees go beyond the cluster stage and go into a state similar to deep hibernation in the winter months but not actual hibernation.
And they virtually close down and appear to be dead.
Many beekeepers check there hives in the winter and assume their bees have died when they are in this state. Sometimes this disturbance can bring them out of this state and cause them use up the hives resources or can cause the to actually die.
How many have cleared out a hive to clean and get ready for the new beekeeping season in mid winter believing the bees have died out when actually they could have been in a Torpor.
On visits to other beekeepers i have taken a handful supposedly dead of bees warmed them in my pocket for 10 minutes and revived them.
This is why you should not open your hive at all during winter just leave them alone stick a large sugar block on top if they need it or not early on when it’s still warm enough to take the lid off.
Giving them an emergency source of food they may or may not need is cheaper than buying bees in the Spring!
I never assume a hive is dead until its warm and dead!!