Jane, Cambridge asked:
Having just discovered that when bees are attacked by something like a hornet they can form a 'bee ball' around it and boil it to death with all the heat generated in this ball, I was wondering whether it is theoretically possible that they could do the same to a human? Given unlimited bees I suppose. I wonder how many you'd need...
We posed this question to Jürgen Tautz, from the University of Würzburg...
Jürgen - So heat from a honeybee is produced by its strongest machine which is the wing muscles used for flight activity usually. So the bees can mechanically decouple their wings and let their flight muscles run full power and this way, a lot of heat is being produced which gets to about 65 millijoule if one takes their energy. The energy for producing this heat is taken from the honey. So the honey which the bees are producing from the nectar, they collect from flowers, this is the stored energy they have to eat first and then transform it into heat.
Diana - And how many bees would have to feast on honey before decupling their wings?
Jürgen - The calculation can go like this: If you assume that a human consists of about 50 litres of pure water, which is close to realistic; and that a human dies at 42 centigrade, which means a human has to be heated up from 36 to 42 centigrade. We need - to heat up 1 gram of water, so one millilitre of water, for 1 degree Celsius - we need 35 joules which means to heat up a human by 6 centigrade, we need 1.5 million joule. If on the other hand, we take the heat which can be produced by a honeybee which is 65 millijoule, it’s very easy now to calculate how many bees we need to heat a human to this extent, which is roughly about 20 million honeybees, which comes close to about 1,000 midsize bee colonies. So not much, space on the surface of a human, to give access to all these bees.
Diana - That’s right. It’s 20 million bees or 1,000 colonies to essentially cook a human. And to heat a person up to 100 degrees, roughly the boiling point of water, you'd need about 250 million bees. That’s 12 ½ thousand colonies or about a 6th of all the hives currently registered in the UK. But you'd only need to feed them 160 million joules worth of honey, which you'd find in about 50 jars of the stuff, and that honey would cost you about 150 quid, which isn’t so bad!
How much heat does a single bee generate? How much heat per pound (or stone) would it take to boil a human? Unless I'm missing something I think it could be calculated if we knew these numbers.
Donnah, this behavior in bees in most commonly used to maintain hive temperature in cold weather. SteveFish, Thu, 18th Nov 2010
We are planning to build a hive near the house with hopes of attracting a wild colony. It's not for the honey; we had very few bees this summer and we want to help boost their numbers.
Donnah, I think you will have to capture a wild hive that is swarming or just buy a queen and some workers. When swarming, bees find all kinds of places acceptable (e.g. hollow logs, house attics) and the chance that they might find a beekeepers hive is very small. You probably have a group of folks in your area who are bee enthusiasts that would help you. Steve SteveFish, Sat, 20th Nov 2010
Good advice, SteveFish, thanks. We saw a V-shaped hive in Mother Earth News we'd like to build and there's attractants you can put on it. We'll continue to round out our knowledge.