Portable queen cell incubator

One of the earliest posts on this site, back in January 2014, described my honey warming cabinet.

Both that post and the cabinet are still going strong.

The cabinet has been used to process a lot of honey … and the post has been read tens of thousands of times and still remains in the top 10% of most read pages (of ~450 now) in 2021.

I attribute the popularity of the post to two things:

  • it was an erudite article written in an elegant and entertaining style 1
  • the design reflected the sort of inspirational genius rarely seen outside a Dyson factory 2
  • almost all beekeepers find that a honey warming cabinet is very useful
  • similar 3 commercial honey warming cabinets are a daft price

Today’s post is on a niche DIY project … a portable queen cell incubator. However, like the honey warming cabinet, it is something that can be built for significantly less than a similar commercial model.

Portable queen cell incubator version 2

Unlike the honey warming cabinet, this is something that will be of interest to only a subset of beekeepers.

Or perhaps fewer.

The fraction of a fraction of a small proportion

Firstly, only a small proportion of beekeepers actively 4 rear queens. Quite how big or small that proportion is I don’t know … perhaps 10%.

Secondly, only a fraction of that 10% of beekeepers will want to use an incubator for queen emergence or short-term storage 5.

And finally, only a fraction of that fraction might need the queen cell incubator to be portable.

But I’m one of them, and I know there are a few others who are regular readers … 6.

It also seemed appropriate to balance the article on frames – of general relevance, if not interest – last week with something of very specialist interest … reflecting the wonderful diversity of our hobby.

Design criteria

I discussed some general features of a portable queen cell incubator when I described my first attempt at building one back in July.

Broadly the design criteria were as follows: 

  • automatic temperature controlled environment maintained at between 33.3 °C (92 °F) and 35.5 °C (96 °F) 7
  • ideally with the temperature controlled to between 34.4 °C to 35 °C (94-95 °F)
  • high humidity
  • able to accommodate at least 10 queen cells in Nicot cages
  • portable and powered by a 5V or 12V supply so it could be used in a car (or from a battery)

Version 1 was a case of ‘close, but no cigar’.

It worked up to a point. Queens emerged in it and I successfully transported virgin queens across Scotland (including hotel stops), maintaining them for up to a week before introducing them (also successfully) into hives. 

Version 1 … a bit primitive if I’m honest … but it did work (more or less)

But it was a bit of a botch-up.

It consisted of a polystyrene box with a 5 V vivarium heat mat. Temperature control was not automatic, but was more sort of ‘hit and hope’.

If at first you don’t succeed … 

However, I’ve spent some time since then making version 2 which – remarkably – meets all of the design criteria listed above 🙂

I don’t intend to provide a step-by-step guide to building this portable queen cell incubator. You might want a bigger one, or one for mains power only, or to house bare cells rather than queens in Nicot cages, or one coloured red or whatever. 

But what I will show are the general ways I met my design criteria, with a list of parts and lots of pictures showing how it was put together. I’ll highlight the critical features that actually made it work as intended. I’ll also discuss testing and performance, which are as important as the design and construction.


The portable queen cell incubator consists of an insulated picnic box with a 12 V 15 W heating element. Supported above the element is a block of foam insulation to hold the Nicot cages. Temperature control is automatic and a very stable temperature is achieved by circulating the air in the incubator with a small fan. Ten Nicot cages can be accommodated at a suitable temperature for hours/days at a time in ~90% humidity.

It’s winter … so this hasn’t been tested with queens or queen cells.

Caveat emptor.

A list of parts is followed by cross-sectional diagram and lots of photos, with comments, of some of the components. Towards the end of the post I describe the testing process and the results.

OK, for the six readers who have not already moved on … buckle up. Here goes.


This is what I used. I didn’t shop around much for bargain prices, so you might be able to do better. Note that I struggled to find anywhere other than RS Components that sold suitable heating mats.

  • Insulated picnic box – e.g. an Andes 5 litre coolbox at £14.99
  • Piece of wooden laminate flooring (from my spares bin)
  • Silicone 15 W heating mat – e.g. one from RS Components at ~£30
  • A5 6mm aluminium sheet – purchased from eBay for £4.50
  • Offcuts of a cheapo plastic queen excluder (from my spares bin)
  • 20 mm M4 roofing nuts and bolts (from my spares bin)
  • Closed cell foam – the stuff they pack computers in when shipping (from my spares bin)
  • 40 mm 12 V computer fan – e.g. a Noiseblocker BlackSilent Fan XM-1-40mm at ~£4.50 8
  • STC-1000 12 V temperature controller – e.g. an Aideepen at £14. Make sure you choose a 12 V model.
  • Plastic food container for the electrics – stolen from the kitchen (from my spares bin)
  • Velcro tape, Sugru, zip ties, cable gland, thin bits of foam, some wire and a few electrical connectors (from my – yes, you guessed it – spares bin)
  • 12 V mains power supply with 5.5 x 2.1 mm male connector (from a woefully poor BT broadband modem via my spares bin)
  • 5.5 x 2.1 mm female power jack sockets (about £9 for half a dozen)
  • 12 V car cigar lighter adaptor with 5.5 x 2.1 mm male connector (about £8) 9

Testing, testing

For development and testing I used a Raspberry Pi Zero with DS18b20 external temperature sensor(s) and DHT22 temperature/humidity sensor to monitor the environment in the incubator. For the technically-minded these recorded internal and external temperatures and/or humidity at 1 minute intervals, displaying the results via ThingSpeak. Perl or python scripts were run via cron jobs and data was saved to CSV-format files for subsequent analysis.

Computer geekery used for testing purposes – Raspberry Pi Zero, two DS18b20 and one DHT22 sensors

You don’t need this type of computer geekery, but you do need to be able to accurately determine the temperature (at least) inside the incubator and to calibrate the STC-1000 thermostatic controller.

Ideally you want a thermometer small enough that you can place it in different locations to determine how even the heating is within the incubator.

Cross-sectional diagram of the queen cell incubator

Early attempts just placing the foam (holding the Nicot cages) directly above the heating element were an abject failure. Temperature control was all over the place.

It turns out that you need a 1 cm gap between the foam and the element and you need a fan to circulate the air. That was the breakthrough … after which it was pretty much plain sailing.

Queen cell incubator schematic

A very humid environment is not ideal for electrical things like fans or thermostats. I therefore opted to house everything except the fan in a plastic food container velcro’d to the outside of the insulated picnic box.

Mission control

Not pretty … but functional.

If I was doing this again I’d do exactly the same thing … it works perfectly well.

Calibrate the STC-1000

The STC-1000 is a widely used and inexpensive thermostatic controller. It has a power input, a temperature sensor (probe) and separate controllable heating and cooling circuits. Both 12 V and 240 V models are available. 

You set the control temperature on the STC-1000 and a delta (offset) temperature of, say, 0.3 °C. Every time temperature drops below the set temperature minus delta the heating circuit switches on. When the sensor reports the temperature exceeds the set temperature plus delta the cooling circuit switches on. In the narrow range of set temperature ± delta the STC-1000 just keeps track of the temperature. 

This project did not use the cooling circuit.

The STC-1000 temperature sensor is on a long piece of wire. It is almost certain that the displayed temperature is not the actual temperature.

Calibrating the STC-1000

I worked out the temperature difference by placing the sensor in a Thermos flask (no lid) of hot water (~50 °C), together with thermometer(s) I trusted. I then recorded the temperatures at 10 minute intervals as the water slowly cooled and plotted the results.

STC-1000 calibration

My STC-1000 consistently over-read by ~1 °C across the tested range (28 – 49 °C). The STC-1000 has a function (F4 in the menu) to calibrate the unit so that the display – and therefore the thermostat settings – reflect the accurate temperature.

It’s worth doing this before embarking on the build, though you will need to adjust it again later (see below).

The F2 function on the STC-1000 sets the temperature delta (offset) away from the set temperature. Set this to the minimum, which is 0.3 °C. You want the temperature to fluctuate over a limited range.

The heating element

This is the single most important and expensive component.

I used a 12 V 15 W 100 x 150 mm silicone heating mat from RS Components. 

WARNING – these heat pads MUST be thermostatically controlled. Without thermostatic control these pads can reach ~200°C. Not only will this cook your queens, it will probably also melt your car, burn your house down and run off with your spouse. You have been warned!

Of course, I immediately wired it up (without a thermostat) to a 12V source and determined that it didn’t reach anything like 200°C particularly fast … though I dare say it would reach it eventually.

It did get too hot to touch, but you have to try these things, don’t you? 10

Silicone heating pad, wooden insulation and aluminium plate

To avoid damaging the inner floor of the box 11 I placed it on top of a ~1.5cm thick offcut of wood laminate flooring. I stopped this moving about with some fillets of closed cell foam.

To help dissipate the heat more evenly I stuck the heating mat to the underside of a 6mm thick piece of aluminium. The heating mat I purchased had an adhesive pad on one side of it.

Make sure the heating mat is central and stuck down with no air bubbles. Protect the wiring from the sharp edges of the aluminium pad with some gaffer tape.

With hindsight, a larger heating mat may work better. RS Components do a 30W version which is A5-sized (approximately) and would fit in the insulated picnic box I used. It should heat the box faster and may provide a more evenly heated surface 12.

The box

I chose a small (5 litre) square-sided picnic box designed to take 6 x cans of beer (or Coke … or iced-tea or whatever). The sides and base are foam-filled. The lid appears to be just hollow plastic. 

The box has a carry handle 13. There is no lock or catch to keep the lid shut, but it is quite tight and should be secure enough.

The intention at the start was to mount the STC-1000 through the side-wall of the insulated box, hence the choice of a square-sided model. I quickly abandoned this idea when I realised the humidity level inside the box and just how limited in volume it was.

There are similar, and slightly bigger insulated sandwich/picnic boxes that might well be better insulated and/or a better choice 14.

The internal bits 15

I drilled a hole through the rear wall of the box to take the wiring for the STC-1000 temperature sensor, heating mat and fan. In addition, I drilled a hole for a thermometer for use when testing the unit (subsequently filled in with a bit of foam and taped over, but it’s there if I need it again).

The foam block to hold the Nicot cages needs to be supported ~1 cm above the aluminium sheet. I used an offcut of plastic queen excluder held in place with 6 ‘legs’ created from M4 roofing bolts. These are a reasonably good fit through the holes in the queen excluder, but require a nut and washer each side to hold them firm and square to the plastic.

Legs for the foam support

This support was placed ‘screwhead down’ on top of the aluminium sheet.

Queen excluder support for foam block

The foam block goes on top of the queen excluder. I had to cut small recesses in the underside of the block to accommodate the protruding ends of the M4 roofing bolts. This is important as it keeps the queen excluder and foam properly aligned and flush fitting.

The foam block must be carefully shaped … this needs:

  • the ability to visualise the finished item in 3D
  • a sharp breadknife
  • a steady hand … or Elastoplast

The idea is to maximise the area to accommodate the Nicot cages, but to allow good airflow around the four edges of the block. I achieved this by leaving protruding corners that fitted very snugly into the box, but cut ~1 cm ‘recesses’ in the block on all four sides.

Foam block corner detail

The foam block I started with was ~5 cm thick, but I thinned it to ~3.5 cm to provide space for the Nicot cages.

My greatest smallest fan

The fan is located centrally, supported at the corners on the queen excluder and attached to the underside of the foam block. I cut a 40 mm diameter central hole through the block using a holesaw and then, using a scalpel, cut a recess for the fan. The fan was just taped in place. The airflow is intended to push warmed air from the aluminium plate UP through the central hole, so make sure you get the fan in the correct orientation.

I discovered that it helps to cut away the queen excluder underneath the fan to maximise the airflow. These little fans are pretty puny … don’t obstruct them if you can avoid it. 

The fan I purchased had a speed controller/reader wire which wasn’t needed, so I just cut it off.

The fan fits centrally in a recess cut into the underside of the foam block

I cut eleven suitably-sized (~2 cm diameter) plugs out of the block using a holesaw for the Nicot cages. Rather than cut right through the foam I cut through partially (~2 cm deep) and then used a very thin and sharp scalpel through the side of the block to cut across the bottom of the plug, so releasing it.

The intention was to grip the Nicot cage, but to have the queen cells protruding into the airspace over the foam … where hopefully the temperature would be even and constant.

Almost finished …

Wiring it all up

I’m not going to embarrass myself or risk your electrocution by showing the gory details of the rats nest of wiring I ended up with.

What a mess … 12V makes this a whole lot easier and safer

Suffice to say that working with 12V probably saved my life more than once 😉

It’s worth remembering that the heating (and cooling) circuits on an STC-1000 are not powered but the temperature sensor is, so you need to take a spur off your power input to provide juice to the heating mat.

I based my wiring on the following diagram, ignoring both the yellow/green earth wires as I was using 12 V and the cooling terminals.

STC-1000 wiring diagram. For 12 V omit the yellow/green earth wires.

Actually, it was a little more complicated than that as I also wired the fan directly into the power so that it was always running. Preliminary tests showed that this gave reduced temperature fluctuations than when wired in parallel with the heating mat.

More ‘shockingly bad’ wiring

The temperature sensor and wires to the heating mat and fan are routed via a cable gland from the plastic box on the outside, through the hole in the sidewall of the picnic box. I sheathed the wires in some flexible cable sleeving I had from another project.

Cable gland and sleeve

The power supply feeds into the plastic ‘control box’ via a near-ubiquitous 5.5 x 2.1 mm socket (shown above). 

The temperature sensor needs to be fixed in a central location on the inside of the lid of the picnic box.

Temperature sensor

To ensure repeatable temperature control this sensor must be in a fixed location. Do not just leave it flapping around in the box 16. Make sure you have sufficient wire free to the sensor to allow the lid to open easily, without fouling anything in the box.

Ready for testing

With everything assembled the inside of the box should look something like this:

Almost ready to go

I still have a little more tidying to do with the wiring to the heating pad and the temperature sensor. They will both be held in place with zip ties and I’m intending to construct a smaller seal on the inner wall using Sugru mouldable silicone glue (which is extraordinary stuff).

The recesses to hold the Nicot queen cages are numbered.

Having put everything together I then tested it 17

Temperature testing

The temperature within the Nicot queen cages is not identical in every position in the box.

It varies, in a very reproducible manner, from position to position 18. The variation between positions is mostly with 1°C, so the aim was to adjust the thermostat so as many of the Nicot cages as possible were within the optimum part of the temperature range.

In the following graph the temperature was measured for 1-2 hours with the Nicot cage containing my testing thermometer in each location, with positions #5 (light bars) or #9 (dark bars) occupied by the water source to maintain humidity. Error bars indicate the standard deviation in each position.

Temperature testing

Red lines indicate the lowest (dashed) and highest (solid) temperatures acceptable for incubating queen cells. Blue lines indicate the low and high limits on the optimum range.

Positions #5 and #11 were consistently warmer. The heating mat must have a ‘hotspot’ in this central region. Position #9 was consistently cooler (and was the most variable position).

Using position #9 for the water source, 8 of the remaining 10 positions maintain the temperature within the optimum range of 34.4 °C to 35 °C. The two outside this range (positions #3 and #10) are only ~0.4 °C cooler.

Nice 🙂

Calibration of the STC-1000 … what, again?

But you will not achieve figures like those above without again calibrating the temperature offset in the STC-1000.

With the temperature sensor suspended from the lid of the box there is a temperature differential between the sensor and the location of the queen cell within the Nicot cage.

You therefore need to work out this difference and then recalibrate – via the F4 function – the offset on the STC-1000. 

Accurately measure the temperature where the queen cells will sit and then compare this temperature with that shown – once a steady temperature is reached – by the STC-1000. For example, if the STC-1000 is set at 34.5 °C, but your thermometer reads the Nicot cage temperature as only 33.5 °C, you need to adjust F4 by -1.0 °C.

This takes a little time, but the goal is to end up with the set temperature on the STC-1000 being the temperature at which you want to incubate your queen cells.

Frankly, I was delighted 19 I could get such accurate and reproducible temperatures 🙂

The ambient temperature in my workshop was 15-17 °C throughout these tests, but I also confirmed that the temperature did not fluctuate when the box was moved outdoors (8 °C).


Queens need a humid environment. I used a folded up piece of kitchen towel fitted tightly into a Nicot cage and then soaked in water. This sits in position #9. Using this I could maintain humidity at a fraction over 90% as long as the lid of the box was closed.

Humidity measurements

From a ‘cold start’ humidity increases to ~91% after one hour and remains high. The humidity drops to ~70% when the box was briefly opened (after 2 hours 40 minutes, above) but quickly returned to over 90%.

That’s good enough for me and should be good enough for my queens 🙂

Heating and cooling

The graph above shows that the box takes about one hour to reach working temperature. In repeated tests this was very reproducible from an ambient (workshop) temperature of ~17 °C.

Heating and cooling

If the lid was kept closed the temperature drops from ~34 °C to ~25 °C in one hour when the power is turned off. The temperature drops much faster if the lid was left open 20.

All of the temperature measurements shown in the bar chart above involved repeated opening and closing the lid to move the test thermometer about. This is not dissimilar to the manipulations when introducing, checking or feeding queens. Under these conditions the temperature fluctuated by only 1-2 °C and returned to the set temperature within a few minutes.

Again, that’s more than good enough for me and my queens 🙂

What’s in a name?

There is a commercial portable queen cell incubator, the Carricell, made in New Zealand.

Carricell queen cell incubator

This is primarily designed to carry cells … hence the name. I don’t think it’s a queen cell incubator, despite what it says on the side of the unit. It keeps cells warm, but you couldn’t incubate sealed cells until they emerged … but what do I know, as I’ve never seen or used one?

I’ve also never seen any data on the temperature stability of the Carricell. However I do know they cost an eye-watering €636 from Swienty (for the mid-sized 70 cell model).

The Carricell is for professional bee farmers who want to transport lots of cells at a time. 

My incubator is for a small number of cells only (but could be scaled up now the basic design problems are solved).

I need a name for the box I’ve described as ‘portable queen cell incubator’ is much too sensible and unwieldy. 

I currently favour the name PortaQueen 21 … can you think of anything better?

In use

Unless you’re in the fraction of a fraction of a small proportion of beekeepers who actually need one of these you might have read 22 the last 3700 words and be wondering “That’s all very well, but what the hell is it used for?”

Here are the three things I expect to use this for next season:

  1. Incubating queen cells started and capped in my cell rearing colonies. This frees up the cell rearing colony to rear a second batch of queens. A capped cell just needs to be kept warm. The queen emerges and is then introduced to a colony for subsequent mating. Alternatively, the queen cell can be used just prior to emergence to prime a newly made up nucleus colony.
  2. Keeping virgin or mated queens warm and safe during transport between apiaries 23. You can feed virgin queens with honey and water and keep them alive for several days prior to introducing them into a colony. It is always good to have a spare queen or two ‘on hand’ in case of emergencies, opportunities or stupidity.
  3. Transporting eggs or very young larvae for grafting in a distant apiary. I don’t have space to write about this more here, but may cover it in the future.

Here’s one I produced earlier

If you attempt to build one of these I’d be interested to hear how you got on.


Almost forgot … this box needs a 12 V supply, but the heating pad and fan are about 16 W total (and the former is only on ~50% of the time). I calculate it could be powered by a 7 Ah sealed lead acid battery for a few hours if needed. Coincidentally (not) I’ve previously built solar powered battery boxes that house 7Ah SLA batteries to drive my trail cameras which could also be used with the PortaQueen.


  1. Er, no it wasn’t.
  2. No it didn’t.
  3. Though less well designed … he modestly claims.
  4. By which I mean deliberately generating more queen cells from selected stock for requeening or sale – irrespective of how they are actually produced … grafting, Miller method or whatever.
  5. I discuss briefly why you might want to at the end of this post.
  6. And since this is my site I can write about whatever the hell I want.
  7. I’ve included temperatures in °F here for the convenience of US readers. I won’t keep on repeating them.
  8. But I’m afraid the price has gone up since then. Both RS Components and CPC Farnell sell suitable models for a few quid.
  9. I also had these last two items from previous projects, but quote indicative pricing.
  10. My motto ‘Live fast, die young … and leave a good looking, albeit slightly charred, corpse’.
  11. When heating its temperature will exceed the ~35°C temperature in the Nicot queen cages.
  12. If the royalties from the sales of this design are sufficiently large I will plough some of them back into the R&D department and ask them to try a 30 W heating mat … don’t hold your breath.
  13. Essential if it’s to be portable.
  14. As before, if the royalties are obscene enough I’ll force the R&D elves to knock up some larger, better insulated versions for testing … don’t hold your breath.
  15. I hope that’s not too technical for you.
  16. Been there, done that … and I know it doesn’t work.
  17. Actually, the only way I knew to put things together in the order described was by testing a load of unsuitable configurations first … but it still needs final testing and calibrating before use.
  18. I think this is because the temperature is dependent upon heat from below – where there are hotspots – and the air temperature, which is pretty even, but this needs further testing.
  19. And more than a little gobsmacked.
  20. No sh1t Sherlock.
  21. Like PortaPotti, but different.
  22. But probably didn’t.
  23. Remember that my apiaries are separated by 150 miles, a ferry and a hotel stay.

40 thoughts on “Portable queen cell incubator

  1. Jason

    Blimey David, that is one epic DIY project. I’ve literally just ordered the parts needed to build myself a honey-warming cabinet (I am one of the repeat readers of that particular post) but this is just on another level. Hats off to you, Sir.

    1. David Post author

      Many thanks Jason

      The construction was pretty straightforward, but the testing and tweaking was time-consuming. However, I’mm pretty confident that the final product is at least as good as a commercial product that would likely cost five times the price.

      It’s also fun to solve this sort of practical problem 🙂

      Have fun making your honey warming cabinet … I’ve even used mine to incubate queen cells, though it’s hardly portable.


  2. Keith

    Hi David. I admire your ingenuity. On a tangent I use one of the reptile incubators that you can get on eBay / marketplace etc for £50/60. It looks like a small beer fridge. They also come with 12v car adaptor. I have a couple of silicon hexagon ice cube trays off Amazon to hold the cells safe and some cotton pads in a plastic food container for humidity.It’s great for transporting to and from the apiary and certainly beats my old cool box with a damp towel and a hot water bottle beneath.

    1. David Post author

      Hi Keith

      I looked at those reptile incubators (and Brinsea egg incubators) and have used tea towels and pre-warmed ‘freezer’ blocks lots of times. Over long periods I’m concerned about the temperature stability using these approaches. At least with the system above I’ve tested it and am confident in the temperature regulation … even though it’s a bit Heath Robinson (which I think is what ingenuity means 😉 ).


    2. Mark Richards

      Hi Keith

      I know it’s a while since you posted about your reptile incubator, but do you have any photos of it as I’m thinking of Mali g one myself?

      1. David Post author

        Hello Mark

        Mali g = making I presume?

        Keith will only see this if he has subscribed to the comments on this post.


  3. Marcus Hughes

    Perhaps as an appropriate name for this a Queensedan or Palanqueen?

    Currently building a hive monitor using the DH22 and DS18b20, plus a few more gizmos to measure weight etc. My cabling looks very much worse than yours, you’ll be happy to know.

    1. David Post author

      Hello Marcus

      Delighted I’m in good company … I’ve also dabbled with hive monitors (both commercial and very amateur). The latter project has been neglected a bit recently but I should revisit it. I’ve got solar power in my sheds but the small Raspberry Pi’s can be stop/started with something like a Witty Pi hat and run for long periods off a battery.


  4. Dave Stokes

    I always read all of your articles; this one is particularly useful for supplying ideas and sources of components for my honey/super warming box. I have no intention of making an incubator even though I have been rearing queens for over 30 years, how does one make up losses with out doing so?
    Almost to my shame, I had not considered power supplies from discarded electronics to power a fan, or that EBay was a source of aluminium sheet.

    Thanks for another interesting read.

    1. David Post author

      Thanks Dave

      I’ve got a small mountain of abandoned power supplies. They come in for all sorts of things. You can buy almost anything on eBay … and for small quantities of stuff it’s often quite reasonably priced (but there are a lot of dodgy crooks there as well 🙁 ).

      As for ‘how to make up losses’ … they beg, borrow or sometimes even steal. But more usually they buy. That’s why tens of thousands of queens a year are imported.



  5. andrew brough

    I made a transfer box it runs on mains and in the car. The difference is it takes the frames with the cells on.
    With a set of supports it holds 3 Nat , 14 x 12 ,and Langstroth. also 6 mating hive frames. So can be used to transfer Cells and frames of Larvae. It has a digital control and can incubate cells covered with roller cages. It has two heating elements 9W reptile mat maintains the temp. And a 26W wine mat to get it to temperature. The controller cost £10. The rest of the materials I had already. And also use it to warm and condition foundation in frames. My trade is scientific instrument maker, designer and problem solver.
    Best regards Andrew

    1. David Post author

      Hi Andrew

      ‘My trade is scientific instrument maker, designer and problem solver’ … you have a distinct advantage then over me then. As I replied to Vince elsewhere in these comments, I have few skills (and create more problems than I solve).

      During the early ‘back of the envelope’ design (Ha!) phases I did consider one to hold frames, but rejected this because of the likely resulting size and portability. I can see that there are certain cases in which it might make sense, but it probably would not fit with my beekeeping/queen rearing.

      I just use a hairdryer to pre-warm old foundation. Quick and easy.


  6. vince poulin

    Recall an older post where I said “Maybe you do not the tools but – you have the skill”? This and many other posts illustrate the breath of you skills David. We are lucky to have you.

    1. David Post author

      Thanks Vince … very kind 🙂
      Fortunately, building this took almost no tools … and, despite the detail above, I don’t think it takes a huge amount of skill in terms of the build itself. I think the difficult bit is calibrating it to be the actual temperature needed, not just the temperature the STC-1000 says it is.


  7. neil lamey

    For the none d.i.y. person a mains / 12volt insect lncubator from incubators on line for about £150., had mine for 4 years and works a treat.

  8. Beekeeping Gardening

    Great tips Thank you for sharing this great information
    O have incubator make from small freezer work really good.cost me £45 everything I can get 500 queen cell in the.
    I will be getting building for transporting incubator queen cell very important for me.
    I will be use your ideas 🐝🐝
    Thank you

  9. Reto

    Very nice post!

    Would you have any pointers as to what environmental conditions are needed to build a brood frame warmer box to combat varroa? There are commercial units available (at a price), but seeing your project I think that itt could be upscaled for a bigger box containing several brood frames to be kept at a temperature that kills varroa, but leaves the brood intact.

    1. David Post author

      Thanks Reto

      This is an area well outside my area of expertise. I think Varroa are sensitive to temperatures above 40°C and that they prefer temperatures at or below 32°C. However, I don’t know how long mites need to be maintained at 40°C to kill them. You’d therefore need a well-insulated box capable of heating frames (and presumably attached bees?) to 40°C. You’d need to work out how long it takes to get to temperature, and how long it needs to stay there to be effective … that’s a very large amount of work. You’d also have to monitor survival of brood and bees afterwards.

      I’ve seen solar hives that are supposed to achieve this … but never seen any evidence that they actually work. And by evidence I mean something other than anecdote!

      Good luck if you give it a try.


        1. David Post author

          Hello Reto

          I couldn’t see any links to proper scientific analysis of efficacy for those. Some meeting reports and articles in beekeeping newsletters perhaps, but no peer-reviewed (or possibly independently reviewed) studies. It’s not an alternative to miticides as it appears as though these still seem to be needed, presumably for all the phoretic mites in the colony. Three treatments per season – including 2 with miticides – each taking 2+ hours per hive is a lot of manual effort … and needs a mains electricity supply. Interesting, certainly. Practical, possibly (for some). Effective and efficient … I’d need to know a lot more.


          1. Reto

            Fair enough, I thought I saw a study when I looked into it some time ago. But It appears the institute who did that test, does not even mention it on their own website. They have quite some information available to beekeepers otherwise.

            Randy Oliver also looked at it briefly, so I may find some more pointers there (once I have the time to read it all 😉 )

          2. David Post author

            Hi Reto

            I should have known that Randy would have looked at these. I’ll have a read as well.

            Many thanks

  10. Martin

    Thanks for this David.
    You have inspired me to get cracking on my own incubation device.
    I need a supers dryer,and a warming cabinet too and wonder if a compromise( already dead in the water…)could be made by combining the functions into one machine.

    I’ve seen this Inkbird controller on the infamous tat-bazaar

    I wonder if the two controller bundle could be of use?
    I love ‘kit’ but having it lying around unused for a large chunk of the year is frustrating!

    1. David Post author

      Hello Martin

      I took the liberty of editing the link to make it more readable …

      I know others who use those Inkbird controllers (or at least similar ones, not sure of the source) very successfully, including for honey warming cabinets. I’ve also used my honey (and super) warming cabinet for queen cells. I never bothered monitoring the humidity, I just put the cells in a plastic container together with a few bits of very damp kitchen paper. This seemed to work.

      It’s worth noting that humidity levels in the hive are lower than those I’ve quoted in the above post. Arnia – the hive monitor people – usually report figures of 40-60% if I remember correctly. There are other reports that state that relative humidity levels below 50% should be avoided in queen cell incubators.

      Personally, I’d just focus on getting the temperature right and then use a simpler way of maintaining a suitably humid environment (as it seems less critical and easier to achieve).


  11. Frazer Munro

    Hi David,
    Yes, I am so going to do this!
    Im sure ive already told you ive been reading like billyo as ive bee n away from bees for 20 years or so, and only recently realised i need to move away from the knowledge my father gave me so many years ago (based on an old copy of Roots and a a few other magazines. The consensus of good practice seems to have stabilised (I hypothesise), thanks to the internet, over some recent years…
    One consensus many authors (Wedmore, Simmins and Br. Adam ) seems to be that Queens do need to be replaced (usually annually) and I am coming to the same conclusion. I also like Mike Palmers idea of overwintering a neuc beside each production colony to both bolster the colony earlier on in the season and to keep a spare Queen in reserve if needed.
    This suggests to me:
    My next year will be bad, as I’ve overwintered a number of 2 year olds.
    I can no longer rely on Snelgrove splits to raise sufficient Queens ….
    That I cannot run my apiary without raising many Queens.
    I was looking at an egg incubator too, but your testing with temperature dispersion helps tremendously and I will not need to repeat this. However…
    I was wondering if a thin smear of heat transfer paste like what is used between CPUs and heat sinks would help?

    PS. re Ebay, It is now my repository for things. IF I dont use something for a while AND I have no impending projects for it, THEN it goes on Ebay. If I need it again, I get it from Ebay.
    I’ve cleaned out my house and my principle other relevant stakeholder is very happy 🙂

    1. David Post author

      Hi Frazer

      Mike talks a whole lot of sense and I really like much of what he promotes in his ‘sustainable apiary’ talks. Queen rearing is probably the most fun you can have with a beesuit on … and once you see how easy it is, you’ll never look back. In my view it is the defining technique that makes beekeeping much, much easier.

      Of course, you only get to realise how easy it is after quite a bit of practise 😉 But don’t let that deter you. Practise makes perfect. The very first time I tried to rear queens (other than straightforward splits of course) I got it to work … perhaps just a couple out of the 10 grafts. Now I’m disappointed if I can’t routinely achieve 70-80%. And I’m sometimes, even now, disappointed, but at least I’ve enjoyed getting disappointed.

      Regarding practicalities. The heat mat I used had a peel-off thin adhesive pad on one side. It made very close contact with the aluminium sheet, and I’d be surprised if it could have been improved with that heat sink paste.

      I wondered when writing the article how else the temperature could be easily recorded. The system I use – a homegrown botch up of Raspberry Pi and DS18b20 probes – is inexpensive but requires some understanding of computers (though I’m happy to share the scripts I use). An alternative might be a data logger … like this one that records temperature and humidity. Although it’s about 3 x the cost of the setup I use, it’s an off the shelf unit and allows the data to be downloaded and saved/graphed. It looks suitable, but note that I’ve not used it.

      Ebay is pretty good for a lot of the small stuff you need for these sorts of projects. Enjoy building your QC incubator … I look forward to seeing the (no doubt better) finished product.


  12. Richard

    Hi David,

    You spurred me on to try to make one for myself. I’m slightly cheating though … I found this one available in the USA and it’s in the post to me at the moment to the UK. 12 V and 240 V plus self-contained. $62.99.


    1. David Post author

      Hi Richard

      That looks pretty useful. It’s not clear from the description, but I assume that’s a small ceramic heater. I looked briefly at that sort when building mine but didn’t know enough about them to take the plunge. The fan looks pretty hefty, possibly twice the diameter of mine. This will probably help equilibrate the temperature within the incubator a little better than mine does. I think it will still be important to check the temperature where the cells will be rather than rely upon the temperature reported by the thermostat … and if there’s a discrepancy I’d expect there to be some sort of delta offset function to whatever the LCD/LED readout is reflects the temperature of your cells.

      Good find 🙂 … I’ll be interested to hear how you get on … please post an update.


  13. Frazer

    Yes, interesting approach.
    Would appreciate an update too Richard.
    Thx for sharing

    Hey David, looks like your estimate of 6 was about right judging by the comments this last week 🙂

    1. David Post author

      I suspect it’s only 6 that have spoken up … the remaining 14,395 are busy soldering in their sheds as I write. It’s going to become the ‘must have’ gadget for beekeeping in 2022 …

      … or perhaps not 😉

      Worth noting that there are a variety of PTC (positive temperature coefficient) or ceramic heating elements available as an alternative solution to the heating element I used. No idea whether they would be suitable, but some of them – like this one – are smaller and significantly less expensive.

      I’m going to focus now on rearing the queens rather than keeping them warm … more than one project in a year involving electrickery is tempting fate 😉


  14. Eduardo Fernandes

    Hi David, tank you for sharing this interesting project. i would add a security thermostat to this project very close to the mat.
    all the best

    1. David Post author

      Hello Eduardo

      I’m not entirely sure I’d know how to do that … and worth noting that the heating pad can get hot to ensure the heat is spread through the incubator. I’m not certain how hot the pad gets, so also would not know what temperature to set a security thermostat to.

      I’m all for safety features though. It’s worth noting that repeated use of the incubator – in my car, various hotels and the apiary – and it’s not given any problems.


  15. Archie McLellan

    Hi David

    I was going to buy a Rcom Insect 70 (the favoured option on Beekeeping Forum) until you mentioned that you had one (or similar) – but nevertheless decided to design and make your own incubator.

    So I skipped the commercial option and made one as you described above, but with the 30 watt heating pad. It works! The temperature took a while to stabilise, possibly because of the more powerful heating mat, and the lack of any cooler – apart from time spent waiting. I’m not sure what the electricity costs me, but I’m leaving the incubator switched on all the time. At the moment I’m in between removing and inserting queen cells.

    This is my first proper year of queen rearing and this device is a great help. My warming cabinet wasn’t very successful as an incubator. I’m still scoring ‘unsatisfactory’ in some areas of QR (especially record keeping) and haven’t settled on a particular MO yet. Maybe I never will!

    Thanks for creating and sharing this.

    1. David Post author

      Hi Archie

      Congratulations … on saving yourself £200, on enjoying the satisfaction of building something and on having a proper go at queen rearing 🙂

      The running costs are trivial (compared to the price of a queen and the satisfaction you’ll get). I’ve got some of those smart plugs you can turn on and off via WiFi and they record KWh per day/week/month and it’s pretty low. When I built mine I calibrated the warming up time and how rapidly it cools when the lid is being open and closed repeatedly. I also did some tests with ‘heat sinks’ (essentially freezer blocks that would retain heat when opening/closing) but don’t remember them making much difference, so they probably aren’t worth trying to improve the temperature stability.

      Mine has been great. I should have made it a bit bigger, but the insulated boxes tend to come in a set of rather similar sizes – 6 small cans, a large picnic or 96 tins of beer.

      The other incubator I have is a Brinsea and the temperature stability and calibration is less good than my bodged build … I also cannot use the Brinsea in the car, though I believe the guts of it do work at 12V.


      1. David Post author

        Hi Archie

        Quick follow-up. I hooked mine up to a smart plug meter (which may tell porkie pies … but is probably OK) and the combination of the fan and 15W heat pad totals 20.3W when running. If on permanently this would cost about 15p/day. However, once at temperature, the pad/fan cycle and so running costs are probably about half that.

        You could run it continuously for over a year if you sell just one ‘spare’ queen 😉

        Welcome to the world of big business/high profit beekeeping …


        1. David Post author

          … and a final word on this. It turns out it’s off rather more than it’s on (so must be pretty well insulated) so uses about 0.15 kWh per day which, at the current rate of £0.34/kWh is ~5p per day. Depending where you source them, 5p is about the price of a single Nicot queen cup for grafting … just to put things in perspective 😉

          Here endeth the lesson on the economics of queen rearing 🙂


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