Calculating bee numbers

[Artisan]

Ah well

 

[gingerbees]

Why would you want to know numbers in such accurate detail - sure something like : a few, half full or bursting at the seams would do you?!!

 

[Blue Spinnaker]

Did you see "The Code" on TV? The bit with the jelly beans?

Then ask 500 people to estimate the number of bees and take the average

 

[jenkinsbrynmair]

My great uncle was a shepherd and he found the easiest way to estimate the number of sheep in a large flock was to count the legs and divide by four.
The same for bees but divide by six?

 

[user 6228]

how many kilometers or miles in a 500gm jar of honey?
if a bee is a 1/10 gram and a bee has a pay load of 0.05gm and on average flys 1km per trip. then its 500/0.05 km or 10,000km per jar or a 1/4 of the distance round the earth. but that not allowing for the refuelling of bees! no wonder they're not happy when you take the honey off them!

 

[RoseCottage]

So if you could weigh the hive at night and then lunchtime the next day you would expect a difference in the reported weight. If you assume little or no significant change in honey stores or comb growth/decline you may have the basis of a figure.

The second key set of assumptions is that you can get an average figure for a honey bee weight from your colony (bees are different weights between colonies - some 'feral' bees build to a smaller cell size and so produce smaller bees whilst others produce more drones). You could get this figure by say catching 100 bees and weighing them as they sat on a frame of known weight. In that 100 you would perhaps need a proportion of drone in a similar ratio of worker to drone brood.

So now you have a figure for the daylight vs nighttime weights and a weight for the average bee in your hive. So you could work out a number of bees out foraging from your hive. A reasonably indicative number but not definitive.

Then you need to decide what % are foragers - 30, 40 or 50%?

Whatever you choose could give you an order if magnitude for that particular moment. This is what you were looking for I believe.

Hard, unsatisfying, work.

Another quick way would be to take a suggestion I got from an experienced keeper recently. He told me that a frame of brood when hatched could cover 3 frames of brood with bees. So what size frames have you, how many cells, how much typically is brood and how many frames are covered at night?

If I have 10 frames of brood with 8 seriously covered and 2 partly covered and each frame supported 5000 cells say...

Could I not say that each of 8 frames had 4,000 bees (@80% brood) and 2 had 2,500 bees (@ 50%). Additionally if bees in summer live 6 weeks or 2 brood cycles on average you could say that a further 60-80% of this figure could still be alive from the 1st brood cycle.
So 37,000 bees plus a further 27,000 or so totalling some 64,000 bees. Looking at your colony you would expect a lot of additional super frames to be required to house them at night. Would your observation bear this out?

Again just an order of magnitude at a given moment.

All the best,
Sam

 

[RoseCottage]

I keep reading that for every pound in weight the bees have flown some 55,000 miles, made some 2 million visits to flowers, and mainly visited flowers within a 2 mile radius of the hive (even on my own labels!)

I have no idea how much water they consume whilst producing honey nor how many times they beat their wings per pound of honey (including when removing moisture)...

Perhaps if I can just stare at my navel a little longer.....Oooh I feel a little dizzy...


Sam

 

[RoseCottage]

I forgot to mention in my first post the challenge of accurate scales. I have scales and 2 women in my home. The scales appear to show considerable inaccuracy between the two girls and the error percentage varies by their mood, time of month, choice of clothing and hairstyle.

So with many thousands of females ...accurate weights could be even harder to achieve...



Sam

 

[oliver90owner]

Sorry for being pedantic but some offerings seem to have been submitted without adequate thought of what is really happening in the hive throughout, say, a daily period.

Let's consider the 10 000km per 500g of honey. Apparently no account taken that bees collect nectar and not honey, even though that same distance (or much more) may be flown to effectively collect nothing more than the colony running needs. Both these and other factors would, I am sure, have been used to estimate the distance travelled per jar of honey produced.

The accurate hive weight, at any particular time, will not reflect all, either. In peak foraging time we hear of a super of honey in less than a week. That is, say, 10kg (rounded estimate); now that 10 kg will be associated with a rather different weight of collected nectar, the excess water (over around, but likely less than 20% in honey) may be anywhere from around 5kg up to around 25kg, and is driven off from the hive during the time for filling the super. It would need quite a bit of modelling to estimate the actual weight of bees in the hive to the nearest one kg, and with very stable foraging rates, too.

Imagine weighing the hive in the evening after a superb foraging day and then reweighing a little before a 'late start' the following day. One could easily be out by the odd 10 000 bees.

These statistics have been carefully assessed/estimated by those doing continuous monitoring of hives over a long period of time. A single measurement is not too enlightening as to the actual truth, especially in a fickle climate like the UK has.

Rose Cottage is correct with all the other variables and these clearly demonstrate the inadequacies of doing it yourself. 20k foragers could indicate 40k hive population (50% foragers or as much as 65k (at 30%).

Indeed, the population is not static either. It could easily be changing by well over a thousand daily, perhaps two thousand (or more) at peak change rate (fewer forager attrition but peak emergence from brood).

All this lot demonstrates really, is the futility of counting bees. A guess to the nearest 5 thousand is good, during the summer; the indication of an expanding or contracting hive population is far more useful. After all, most of those bees will be dead in 6 weeks time during the summer months.

 

[Silly Bee]

If you need to know, cant you just take out a full frame, make a square cage of thorns, trap a number of bees, count them, then multiply by the area of the fram.

A square about 2"x2". count the bees, work out the area of the frame, and multiply.

 

[Monsieur Abeille]

Artisan's link http://www.dave- cushman.net/bee/beesest.html#, but remove the space. May be of little importance or accuracy, but none the less interesting for it

 

[Nellie]

Just for some context, I found the formula playing with google because I found it an interesting question, I'm certainly not pushing it as "accurate" but I've found the discussion, and indeed the original formula, very interesting.

However you approach answering the question you'll get at best a rough estimate. with regards to that formula, it is simplistic at first glance, the assumption that only 1/3rd of a colony are active foragers is perhaps less problematic than accepting the 0.0138 variable at face value in the equation.

While pottering around looking for information relating to the original question I found an interesting program dealing with a related conundrum which is apparently well known in maths called the "travelling salesman problem". The program attempts to deal with it in the context of a beehive. Is the underlying maths accurate? No idea.

If you can be bothered to download Visual Studio express, you should be able to compile the program to work on windows and you can play with it, see how you get on:

http://msdn.microsoft.com/en-gb/magazine/gg983491.aspx

 

[SixFooter]

Then change the formula to match your assumptions
0.0138 is also a variable and essentially impossible to calculate in any meaningful sense. At least for us. It's an estimate (guesstimate).

This is like a tree-hugger's calculation. All you need is a number to convert to the number of tons of carbon saved.

 

[Illo]

Well now, what a can of worms this turned out to be.

I was rather hoping someone would say..."oh, take the number of (for example) seams of bees and multiply by (some suitable constant determined by frame size) and this will give you a first order approximation for a reasonably strong colony coming through the summer.

How naive to assume such simplicity!

Thanks everyone for all the responses though...much more fun and fascinating reading.

LJ

 

[Finman]

.
A worker's weight is about 100 mg.
When the bee is full of honey like in a swarm, the weight is 170 mg.

One kilo empty bees is 10 000 bees.

Weight of drone and virgin queen is 170 mg