Bee's generate a lot of heat.

[Aerindel]

Okay, we know that already but I'm really surprised how much they do to warm up their hive.

All day its been alternating between snow and rain here, temps have been in the mid 30's.

Just out of curiosity I took my outdoor wireless thermometer and stuck it inside the mostly empty top medium box of my hive. There where bees down below the meter but this is the air temp in an empty box, not cluster temp.

Outside temp, 34.5º
Inside hive temp 60.2º

I can only guess what the cluster temp is but I think I'm going to buy another wireless thermometer and stick it in a frame and let the bees draw comb around it and integrate it into the hive so this winter I can see what the bees core temp is.

This also got me wondering if anyone knows what temperature kills adult bees and what how warm brood has to stay to remain viable?

[Michael Bush]

Bees generate heat by taking their wing's out of gear and pulsating their wing muscles. Then they fly those same muscles are generating heat. Heat loss depends on sunshine, wind etc. So it's hard to say what temperature outside will kill an adult bee, but one at rest at anything below 50 F will get lethargic and once they can't move anymore they can't generate heat anymore. So an adult on a sunny calm day that is flying might manage to do so at 27 F (I have observed that rarely) But on a cloudy day at 27 F they would all die if they attempted the same thing. Brood has to stay 93 F most of the time. A dip and a rise now and then they can take but consistently higher or lower will kill brood. The winter cluster is that warm IF they are rearing brood. They are much less warm if they are not rearing brood, usually down in the mid 80s F.

[Scrapfe]

... Just out of curiosity... wondering if anyone knows what temperature kills adult bees and what how warm brood has to stay to remain viable?

118 degrees f to 122 degrees f will kill a honeybee according to this link. http://en.wikipedia.org/wiki/Japanese_giant_hornet

[sqkcrk]

Core temp of a cluster in May was read at approximately 98 degrees when we did a study back in college. Just outside the cluster, inside the hive, the temp was almost the same as outside the hive.