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Colony growth – putting it all together

The colony growth model is now more or less complete, I have worked up the math for how a bee population can progress thru the season, as well as the math for varroa mite populations. You can read about the details behind the math here.

So the next question, how realistic is this model, ie, does it truely represent what we see out here in the real world. The proof is in the pudding so to speak, so lets walk thru an example which is VERY typical of what we see happen with new beekeepers in our area, particularly those with an inclination toward ‘natural beekeeping’, ie, no management of varroa.

A very typical start is easy to set up. Open the colony growth model in a new tab with this link. Set the start conditions to a typical new start for our area, a 4 frame nuc started on May 15, queen starts to slow down on Sept 1 and the bees will start evicting the drones by Sept 15. The lines will show a very typical colony growth trajectory that ends with roughly 9 frames of bees for the winter cluster. Now lets assume this colony is very isolated, and catches no mites thru drift, but, it arrived with 1 mite, so select 1 mite in the starting mite population. The end result has virtually no impact on the overall colony, which will end the season with 9 frames of bees, and a 0.6% mite load with a total of 172 mites. This looks like a healthy productive colony of bees, and it’s easy now to start thinking ‘I have no mites, never saw any mites, and the bees look good without any form of treatment, I have good bees that deal with mites’. this is a strong colony with a great looking population of healthy winter bees.

So now lets follow this colony into it’s second season. Start conditions for season 2 will be 9 frames of bees in a wintered unit that starts brooding on March 1. As you can immediately see, the colony grows to the same strength is did the year prior, but gets there earlier in the season. This is an expected difference, with a larger starting population we can expect the initial brood cycles to produce more brood. But there is yet a hidden gotcha, the starting mite population is still set to one mite, and if we look at the results from the end of last year, the colony went into winter with 172 mites. Lets assume a big chunk of the mites didn’t survive the winter, so set the starting mite population to 100 mites to account for almost half of them not surviving the winter.

Now look carefully at that graph of the colony that started the year as a healthy strong colony, 9 frames of bees to begin the season, but they had 100 mites at the start too. Right around Sept 1 you see the mite population is greater than the brood population, which means virtually EVERY brood cell will be infested with a varroa mite. Those are the brood that _should_ be making up the healthy winter bee population, but, they are now emerging as sick bees infested with mite vectored virus. From the outside, this colony doesn’t look to bad in the Sept 1 timeframe, still a healthy batch of foragers coming and going, they made a decent honey crop because there was a good forager population during the honey flow, but the exploding mite population has decimated this colony. By the time they are finished brooding, there isn’t a healthy bee left in the colony, and by the mid November to early December timeframe, there are virtually no bees left.

This mirrors almost exactly what we see over and over. Somebody new to bees starts a colony and doesn’t seem to have a problem with mites in the first year, so they erroneously come to the conclusion ‘I have good bees, they deal with mites fine without a beekeeper intervention’. thru the second year they smugly pay lip service to the old timers saying ‘you need to manage varroa mites’ because, they know, those bees did fine last year with no management. And then by November we see postings on various online sites saying ‘My bees just absconded, why would they do that so late in the season?’. The answer is, they did not abscond, they died. What happened was, that varroa population was growing exponentially thru the season, and then when the time came for the bees to start raising long lived winter bees to carry the population thru the upcoming winter, they were only raising sick bees totally infested with varroa mites in the cells while developing.

So, armed with the knowledge of what happens later in the season in your colony that starts out with 100 mites, the beauty of having a model, we can experiment with options and play the ‘what if’ game. The exercise at this point then, can you find a series of treatment options that will allow your colony started with 100 mites to end the season with a healthy population of winter bees, and 200 or less mites. With the formic acid flash and OAV in your mite control toolbox, the answer is yes you can, but, it will take no less than 8 applications of OAV to keep this colony as healthy at the end of the season as it was at the start.

The real answer to mite control, start the season with fewer mites.

My old comb building experiment

A few years ago I was intrigued by much of the chatter online regarding various ways and means of co-ercing the bees to build more comb, faster. One premise that I read over and over, bees will build foundationless faster than building on foundation, and they will only build comb on plastic if absolutely forced. I did a very crude little experiment to test this hypothesis for myself. Granted, my experiment was not statistically significant, N=1 is not a valid statistical set, but, this was rather enlightening for me. My method was simple, very simple, present the bees with the foundationless, and plastic foundation, on the same frame. The test setup

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Some time later, we removed the frame from the hive and took a photo.

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A quick measurement of how much comb we found in the empty space, and how much was on the plastic foundation gave me the answer I was looking for, and that answer was, no appreciable difference between the two halves of this frame, placed in this hive.

This last weekend we attended the BCHPA annual meeting and the associated education days. One of the sessions I sat in on was a presentation by Randy Oliver describing the correct way to go about a real ‘experiment’ and produce acceptable valid conclusions. My simple comb building experiment was essentially ‘all wrong’, about the only thing right with this one, indeed there was a test case, and a control, subject to identical conditions. That part was easy, the test and control were both on the same frame, placed in the same hive. the result isn’t truely valid because we had only one frame in one hive, so, no other hives replicating this result, and N=1 is not a valid statistical answer. But I also learned, this would be a relatively strait forward experiment to repeat, but, in a more formal manner to produce a result that would be accepted as a real ‘practical research result’.

For those that know me, they know I am big on doing applied research to get practical results that have implications for our business. Next season, during the main flow, we will have more than enough colonies building in 4 over 4 nucleus configurations to repeat this experiment in a manner that can generate a statistically significant result.

The question we asked before, will bees build more comb in a foundationless frame than on a frame with plastic foundation? Randy would say, the correct answer is ‘I dont know’, because we dont have data to show a definitive answer. I have _some_ data, but not enough to be definitive, so I’ll qualify my answer as ‘I dont think so’, but now I’m a bit inspired to produce a real answer, and this is a real answer that’s easily within reach. I’ve got 6 months to write up a proper experiment protocol which can be executed next season during our spring flow, and produce a real answer to this question.

This is going to be fun….

Another Hive scale

Last fall we were intrigued by the simplicity of the hive scale system from the folks at BroodMinder. I ordered one of the scales and a couple of the hive temperature and humidity monitors. Initially there were some problems with battery life, and I set the project on the shelf for the winter, didn’t want to be opening a colony weekly all winter to change batteries in the temp monitor. Last month I dug all that stuff out again when Jeff Lee from the BCHPA stopped by for an afternoon, and it left me inspired to finish setting up and starting a serious evaluation of the gadgets.

My conclusion now, the battery issues I had were just one defective unit, the other two units ran fine all winter stuffed in the closet. The scale went under a hive beside the already existing hive scale, and the temp / humidity gadget is now in the hive that has had a scale for years.

The Broodminder scale is a relatively simple gadget, lots of information at the Broodminder website. It is essentially a bar scale with two load sensors packaged up in a form factor similar in size to a 2×4. To use it, cut a piece of 2×4 to the width of the hive, and set that under the front or back of the hive, then set the scale under the other end. The easiest way to retrieve data from the unit is to simply walk up to it and use a smartphone with bluetooth.

For our installation I wanted live data coming to the website the same way the other scale works, so ofc I did not go the easy route for fetching data from these units. I put together a raspberry pi computer with bluetooth and set it beside the hives in a box, then wrote a small program that retrieves the data from the bluetooth LE advertisements coming from both the scale and the temperature sensor, then fed that data back into the same database we use for the first scale we set up.

I wanted to get a good evaluation of the unit in action, so it’s under a hive right beside the existing scale hive, and I’ve put live graphs from this one together with the original on this website. Looking at the data now that it’s been collecting for a while, I think this unit is very useable. It is by no means ‘perfect’ and it will take some effort in understanding to get ‘science grade’ data out of this one, but that’s really a minor detail. There is some temperature sensativity in the load cells apparent in the graphs, but it should not be difficult to account for, the scale includes a temperature sensor, so it’ll just be a task of getting the temperature co-efficients for those particular load cells. The preliminary graphs I have posted include both the left and right load cell readings, as well as the average of those two in 3 separate lines. The big spike a few days ago is another dump of snow that came down.

Preliminary graphs from the BroodMinder scale.

The theory behind this unit is fairly simple. If we have a scale under the back side of the hive, and a 2×4 pry under the front to keep it level, the scale should be registering roughly half of the hive weight. The theory is sound, and if you are just after accurate approximations of hive progress during a flow, the Broodminder scale ‘out of the box’ is more than sufficient. If you want science grade data from the unit, that too is fairly easy to accomplish, just buy two and use a second scale instead of a 2×4 pry under the other end of the hive, then add the two weights together. I haven’t started to investigate temperature corrections yet, but it shouldn’t be difficult. With temp corrections applied for the load cells, graphs from this unit should indeed be as smooth as they are from the original scale which does have temperature corrections applied to it’s data.

When we first set up the hive scale, the original intent was to get an accurate understanding of the flows in our new area after we bought this property and started turning it into Rozehaven Farm. For that purpose, getting to understand the specifics of flows in any given location, this scale is more than adaquate. We track the dates when we see various blooms, and correlate that with data from the scale. This data set allows us to better understand which blooms produce the nectar that turns into honey in our colonies. When we first moved here, the mantra on this part of the island was ‘blackberries are the main flow’. Today, I dont agree with that older mantra, and we have hard data to back it up. Over 3 years of data collection, our hives on the lot here have never gained any significant weight over the blackberry flow. The early honey comes from the series of blooms that preceed the blackberry bloom, and in our case, the start of the blackberry bloom is now our cue to remove honey supers and extract the early honey. We take the time after pulling supers to prepare our colonies for the move up to Fireweed.

For somebody interested in honey production, I think the Broodminder scale can be an invaluable asset in evaluating yard locations. It’s fully self contained and requires no outside infrastructure to use. Simply place a colony at a new location, set the Broodminder scale under it, then collect your data later using your phone. You will get a nice pretty graph showing exactly when the colony was bringing in enough surplus nectar to store it as honey. We are considering a couple of new outyards as we slowly expand our bee operation, and I think those locations will get a colony this summer that is sitting on a Broodminder scale to give us a detailed record of how well each location can do in terms of honey production over the season, and help us with learning to better time hive placement for catching flows.

Scale problems solved – I think

The erratic readings from the scale under a hive have been a problem since some time in December, and it seemed to get a lot worse after we moved the system from a spot on the lawn behind the house, out to the hive stands which now have a power plug installed.  At first I thought it may be wind or rain affecting things differently in the new location, but, in the end I became convinced the scale itself was the root cause of the problem, so I ordered a replacement.  Same scale from the same source, just a brand new one.

The new scale is in place, and like magic, the readings seem to have stablized dramatically.  We are using an inexpensive platform scale for this project, it’s not built to withstand the weather, and it is a single point load cell.  I’m not sure this type of load cell is meant to have a weight on it constantly over the long term, and I suspect over time the cell has possibly just bent a little internally, ie we essentially wore it out.  In the end it doesn’t really matter why the system became unstable, it had to be fixed.  Purchase cost of a replacement scale is in the same ballpark as buying one package or nuc in the spring.  Live data from a hive thru the spring flow has become a very important input for our strategies managing and in some cases micro-managing the hives for honey production.  With 15 hives set to produce honey this spring, scale data has more value to me than another hive, so this was money well spent.