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Thermal imaging for beekeepers

Last week, a dusting of snow showed me exactly where the cluster in my top-bar hive had gathered. Dead center on the uninsulated gabled roof were two circles of meltwater, so I knew the cluster was right below it. “Aha!” I said. “When my Flir One thermal imager arrives, I will test it on the top-bar hive.”

Sure enough, my very first thermal image showed the cluster centered top-to-bottom and left-to-right. There is something reassuring about viewing it, all snug and glowy, in the middle of winter.

Here is my top-bar hive with the cluster right in the middle. © Rusty Burlew.

Heat converted to visual images

So here are a few observations on my first attempts at thermal imaging. My husband helped me with this post by providing the comments in the gray boxes. He said the information comes from a Wikipedia article on thermography, the specifications of the Flir One, and his vast knowledge of engineering.

This thermal image was taken of the front of hive #4 and clearly shows the position of the cluster. The other two hives on this stand are empty. © Rusty Burlew.

Thermal imagers work by converting heat into electronic signals which can then be recorded and viewed on a video monitor. The Flir One imagers designed to work with smart phones have two lenses, one to take a normal digital photograph of the scene, and one to sense heat gradients. In the final photo, the heat gradient is overlaid on the photograph so you can see where the heat is coming from.

This is the back of hive #4. Because the cluster is in the front, the wooden in the back is less warm. © Rusty Burlew.

Thermal imagers do not “see” inside the hive, but rather they detect heat coming from the hive. For example, the two photos shown here were taken of the same hive, one from the front and one from the back. From the front, the cluster is clearly visible, but from the back it is not. This tells me that the cluster is very close to the front of the hive because the wood in the front is warm.

Since the thermal imager detects heat, it does not show the cluster from the back of the hive because the wood back there is not nearly as warm. From the bees’ point of view, it makes sense that this cluster is in the front of the hive because that is the side facing the sun. The bees take advantage of existing heat whenever they can.

Rich says: In a nutshell, what the beekeeper is seeing is the heating of the wooden hive caused by radiant and convective heat transfer from the cluster to the walls of the hive. In turn, the emissivity of the wood is detected by the camera and converted to visible light, allowing the beekeeper to inspect the hive non-invasively.

A single image, taken from one side of the hive can reveal a source of heat, which is good evidence that there is a colony present in the hive. This single image obviously reveals the height of the colony. This alone is useful because a colony that is very high in the hive may be out of food and need supplementary feed.

An image from two adjacent sides, or even three or four sides, will help triangulate the location of the colony in longitude and latitude. The colony not appearing on one or more of the sides is likely to indicate the colony is distal from the image side, or that a draft within the hive is cooling the inner surface on that side. It is very unlikely that this result is indicative of a camera failure.

Features included in the Flir One

These little cameras are loaded with features. You can choose different color palettes to view the photos either before or after you take the picture. Different palettes show the heat gradients in different ways. You can easily take the photos and then scroll through the pallets to find the one that tells you the most.

The Flir One offers a choice of color palettes. Generally, the user should choose one that gives detail on the temperature gradient. For example, a large white mass provides less information on the cluster of bees than an image with white in the center and multiple colored rings. The finer gradient image helps in deducing where the center of the cluster is.

You can also read the temperature in degrees C or F, or turn that feature off so you don’t see it in the photo. With a single swipe of the screen, you can remove the thermal image overlay and see the plain digital photo underneath which is helpful to better see where things are.

Thermal images around the house

As soon as Rich saw the thermal images, he (mis)appropriated my phone to take photos of windows, doors, and roof penetrations looking for heat leaks. Plus he discovered that the dog’s nose is really warm, white hot actually. Just saying.

The Flir One is useful for finding thermal leaks on houses. This is not a frequent use, but repairing these leaks, which can occur when water is entering too, saves energy, improves comfort for occupants, and prevents damage from becoming even more costly to repair as the problem lingers undetected.

This hive is behind our pump house. You can see the cluster and also some heat leaking out of the upper entrance. The pump house has a heater inside to keep it from freezing, and you can see heat leaking out around the foundation.

The range of temperatures for thermographic images is -50°C to over 2000°C. The Flir One IR cameras operate in a much narrower range, with a “scene” temperature of 32°F to 212°F, perfect for beekeepers checking hives and homeowners looking for thermal leaks at their home. The Flir One may not be a good choice for a technician analyzing the performance of a boiler producing super-heated steam because its range of performance is too low. Infrared film is sensitive in the range of 250°C to 500°C, also of little use to beekeepers.

Worth the price if you can save some bees

I was amazed to see the bees in hive #3 were in the candy board or just below it. The upper entrance you see is between the upper brood box and the candy board feeder. © Rusty Burlew.

Although I was hesitant to plop down money for the imager, I believe it may have already saved two hives. All my hives have candy boards in place, and I had no intention of checking on them further until the first of the year. But much to my amazement, the images show that two of my colonies have already moved up into the candy boards. I knew they were short of food going into fall, but this was unexpected. Time to buy more sugar.

I was first convinced of the value of these cameras when I saw the images taken by Maine beekeeper, Judith Stanton. She saw a mouse nest in her hive and was able to take it out before it did serious damage. Awesome. The take-home message here is important: if you see something weird in your photo, don’t blame the camera. Instead, open that hive the first chance you get.

Open your hive, share your finds

If you are confused by the results of a thermographic image, you should consider opening the hive to learn what is happening. Then you can inform everyone, through a comment, of what the anomalous observation was and what you found in the hive so that we all learn more.

I’m in the process of setting up a gallery of hive thermal images. If you want to include your photos, you can email them to me ( Be sure to say where in the world you are.

Honey Bee Suite

Flir One for iOS and Android are available on Amazon.

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Fall hive management: dealing with dinks

You have a small colony of honey bees that seems to have stalled. The frames of bees look normal enough, and they contain brood, honey, pollen, and a seemingly healthy queen. The bees are performing normal honey bee activities, but the colony doesn’t seem to thrive. Instead it just persists. Although the entire colony covers just two, three, or four frames, the bees seem happy with the status quo.

As a beekeeper, you are perplexed. What do you do with it? Can you get them through winter? Should you even try?

Colonies like this are often called “dinks.” They have been around as long as beekeepers, and every fall the same questions come up. Should you feed them, combine them, destroy them, shake them out, or just ignore them?

1 dink + 1 dink = 1 dink?

The truth is, over the years I’ve changed my philosophy about these grapefruit-sized clusters. When I first started out, I frequently heard the advice that a dink plus a dink equals a dink.

The thought was that if you combined two weak colonies, the combined colony will still be weak and unable to make it through the winter. So it was considered a stupid thing to do.

Instead, I was told to combine a weak colony with a strong one so that I wouldn’t lose any bees. The problem with this idea is that it assumes the dinky colony is healthy and won’t harm the strong one. But is that true?

Any colony that under performs does so for a reason. We might never know what the reason is or whether it is contagious. But unless we know for sure, why risk passing the condition to a strong and healthy colony?

For example, if the dink is weak because it is malnourished or headed by a defective queen, there is little harm in combining. But if the dink is weak because of a pathogen or parasite, we certainly would not want to introduce that into a healthy colony.

So common sense tells us that if we combine two dinks and the resulting colony dies, we haven’t lost much. But if we combine a dink and a thriving colony and the resulting colony dies, we have lost in a big way.

Shaking is worse than combining

Here’s another bad piece of advice I frequently hear: Simply shake the bees out of the dink at the edge of the apiary so the individual bees can move into other hives. In my opinion, this is worse than combining the dink with a good colony. By shaking a diseased dink, you can easily pass whatever it is to all your other colonies at once. How utterly efficient!

So what should you do?

Usually, I start thinking about dinks in August when I evaluate the hives for mites. If I have any hives that appear weak, I start by doing a thorough inspection. I lift every frame and check for brood diseases, I look at the brood pattern, count mites, and check for winter stores.

If I have more than one dink, and they appear healthy except for mites, I combine them before mite treatments. If I have only one, or if I have two with drastically different mite loads, I keep them separate and treat the one that needs it. The next decision is whether I want to overwinter these mini colonies.

Another old adage proclaims that “once a dink always a dink.” I don’t believe this is true. In fact, at times I have been shocked by the turnaround a dink can make, especially when you keep it well fed. It almost seems like they have an internal timer. Once their time comes, they’re off like race horses.

Cost/benefit ratio

The problem, as I see it, is that these small colonies can take a lot of work. If you are willing to put in the effort, you can often turn them around. If you are already pressed for time, it may not be worth it. So at this point, I’d say it’s a personal decision.

When I say lots of work I mean the bees may need constant feeding, they may need pollen sub, they may need insulation, they may need protection from robbers and wasps, they may need windbreaks and rain shelters. In other words, you personally have to make up for the small population. Your role changes from “beekeeper” to “ginormous nurse bee,” at least until the colony gets through the rough spots.

If you succeed, it can be quite rewarding. But if you fail you’ll wonder whatever possessed you to think you could keep the thing alive. I know because I’ve done both.

Honey Bee Suite

Can this dink turn around?
Can this dink be saved? Pixabay photo.

My hives have no brood! What should I do?

It is October or perhaps November. You open your hives for a quick inspection only to find there is no brood. None!  Not a single cell, capped or otherwise. You panic, wondering whether you should replace your queens (tricky this time of year), combine your colonies, or just give up. You blame mites, mite treatments, predators, diseases, bad weather, weak queens, and yourself.

So what is wrong with these colonies? My first guess is “absolutely nothing.” Your colonies have little or no brood because it’s that time of year. Here in the northern hemisphere, brood rearing slows dramatically or stops altogether as the weather begins to cool.

The winter brood nest

Beekeeping in Western Canada, a thorough all-purpose beekeeping book published by Alberta Agriculture and Rural Development, explains it like this (p.6):

As fall progresses, egg-laying by the queen generally ceases, and there is a period of from one to three months during winter when there is little or no brood rearing.

The ABC & XYZ of Bee Culture (p. 43) tells us that brood rearing begins anew after the winter solstice:

Brood rearing begins in mid-winter (end of December to January in temperate climates), accelerates in late winter and early spring, reaches a peak soon after the first forage becomes available, reduces later in the summer, and ceases entirely in autumn. (emphasis added)

Consider these two statements together and you can see that one to three months before the winter solstice puts you back in October. So basically, you may have no brood in the months of October, November, and December.

Variations due to temperature

The actual beginning of broodlessness will vary with local conditions, as will the length of time. Colonies further south where winter temperatures remain mild, may never be completely broodless. Still, even in the south, the amount of brood is lower in the winter.

My own observation is that the length of time (the one to three months) is not the same every year, but is dependent on local weather conditions. So maybe last year, for example, broodlessness started later. Maybe you didn’t notice it because your hives were already buttoned up for the winter. If broodlessness comes earlier in the year, you are more apt to notice it.

Advantages of a small or missing brood nest

All species evolve in ways that help them survive. A period of broodlessness may have a number of advantages:

  • Some researchers have suggested that a broodless stretch allows the queen a period of rejuvenation. She gets to rest and build her strength before the next onslaught of egg-laying.
  • The broodless period reduces the population of the hive by attrition. As bees die, fewer are left to feed. There is an optimum population level for any colony, one that is large enough to keep the colony warm but small enough that the food supply will last till spring. Colony size in winter varies, but it is highly dependent on sub-species. Carniolans, for example, overwinter with smaller colonies than Italians.
  • A broodless period also conserves energy in another way. When no brood is present, the cluster is maintained at a temperature of around 20°C (68°F) in the center. Conversely, a cluster with brood is maintained at about 34°C (93°F). To sustain this higher temperature, the bees must eat a much greater amount of food. So as you can see, a long broodless period is a significant energy-saving strategy.

The Hive and the Honey Bee (2014, p. 89) sums it all up:

There is little or no brood rearing during the coldest part of the winter and colonies reach their lowest population size as winter progresses. However, in late winter the queen begins to lay and brood rearing commences. This requires that workers elevate the temperature to 34-35 degrees C inside the cluster around the brood.

Colony size is not static

Colony size and the amount of brood rearing is in a constant state of flux—nothing about a honey bee colony is static. I’ve written this many times before, but there is a simple rule of thumb to help you remember what is happening inside your hive. Just divide the year into two parts, the growing part and the shrinking part.

Basically a honey bee colony increases in population from the winter solstice to the summer solstice and decreases from the summer solstice to the winter solstice. Adult populations are highest just before the downturn (late June) and lowest just before the upturn (late December).

This schedule is not intuitive, especially to a new beekeeper, so it takes some thinking. The ABC & XYZ of Bee Culture states it like this:

The striking thing about this pattern is that it is so different from the pattern of when forage is available.

But when you think about it, a colony must build up before the major honey flow if the bees are to take advantage of it and store it for winter. Likewise, the colony needs to shrink before extreme cold sets in so food supplies are not rapidly consumed.

Think like a bee

When it comes to understanding your colony population dynamics, it helps to think like a bee. And a bee, it seems, is a good planner with the goal of protecting the future of the colony. My advice is to read a good book on bee biology and plot brood expansion and contraction on a calendar. You will then know what to expect before you open your hive.

Honey Bee Suite

A nice long break sounds like a plan. Pixabay photo.

When is it too cold to open a hive?

My ancestors were hardy Pennsylvania Germans. They were diligent, clear thinking, and not predisposed to nonsense. Whenever I said something lacking in common sense—what they called horse sense—I got the withering glare, the one that said, “You’re no kin of mine.”

No trait is more firmly etched on my brain than common sense and I became, for better or worse, especially adept at delivering the withering glare. So when someone asks a question like the one below, I’m always grateful there are two computers, a piece of black tape, and a bunch of miles between us.

“I think my bees are starving to death. A month ago the frames were empty and I was counting on the fall flow to fill them up. But now so many bees are dead and it’s too cold for me to open the hive and feed them. Help! What should I do?”

I hardly know where to begin. Ignoring the fact that she lost a month by relying on a mere possibility, it’s the cold comment that really sends me. How can it possibly be too cold to feed them?

Her choices are obvious. She can choose to not feed because it’s “too cold” and lose the entire colony to starvation. Or she can open the hive, feed the colony, and lose some bees to the cold. Where’s the question?

Furthermore, cold losses are usually associated with chilled brood. A colony that’s starving will have little or no brood, having consumed it to conserve energy and resources. And even if there is brood, how long does it take to feed a colony? Certainly all the brood won’t die in the 10 seconds it takes to slide in a sugar cake.

Simply put, there is almost no temperature at which it is too cold to feed a starving colony. Sure, there are exceptions. If you’re in the prairie provinces and it’s 40 below, it’s probably a wasted effort. But most beekeepers can find a warmish day even in the dead of winter.

What’s warmish? It depends on how bad the situation is. Starvation is bad and deserves prompt attention. So is disease.

“I want to treat my hives by dribbling oxalic acid. I bought all the stuff, but now it’s too cold to treat. My white board gets about 50 mites overnight. What should I do? Just wait till spring?”

The same advice applies here, although it may be too late. His choices: treat and maybe save the colony or don’t treat and lose it to mites. Fall colonies are low on brood anyway, so there isn’t much brood to chill. Furthermore, it doesn’t take much time to dribble a colony. I can do one in 30 or 40 seconds, start to finish. If you can’t do it fast, practice with syrup and an empty box until you can.

Preparation is key

Before I open a hive in winter, I prepare thoroughly. I make sure I have all the equipment I will need at the site, and then I review my movements. The colder it is, the longer I review.

For example, I once combined two hives at 22 degrees F. One colony thoughtfully left it’s dead queen where I could see it on the landing board. Nice touch. Since I couldn’t re-queen in the dead of winter, I decided to combine it with a neighboring hive.

When I reviewed my steps, it became obvious that I could put the sheet of newspaper over the receiving hive the instant I opened it. This would keep the bees in place and prevent most of the heat from escaping. The queenless hive was in two partially-filled boxes, but the temperature wasn’t right for fiddling with frames. So I took off the telescoping cover (to lighten the load) and taped over the hole in the inner cover to conserve heat. Then I broke the propolis seals with my hive tool. When all was ready, the actual combination took less than a minute.

I removed the lid off the receiving hive, laid down the paper, moved the upper box of the queenless hive to one side, set the lower box on the newspaper, added the upper box, pulled the tape off the inner cover and added the lid.

How many bees died? I don’t know but certainly some. More important, however, is that I ended up with a thriving colony in the spring which I later split into two again.

Don’t assume you can’t do it

The point of all this is that you shouldn’t assume it is too cold to do something to your hives. Think about the consequences of not doing vs the benefits of doing. Compare potential losses. And once you’ve made a decision, plan your steps, review your plan, and go for it. It’s almost never too cold to open a hive.

Honey Bee Suite

One of my favorite bee stories comes from A Sting in the Tale: My Adventures with Bumblebees by Dave Goulson. He needed to destroy a colony of bumble bees because they were imported into the country and could not be released. Hoping to kill them in the most humane way possible, he decided to freeze them. He placed the entire colony into a freezer at -30°C (-22°F). When he went to get them the next morning, he was amazed to find the workers tightly surrounding the brood and queen, buzzing loudly. All the bees were perfectly fine.

Is it too cold to open a hive?
It’s not too cold to open a hive that needs attention, even in snow. Pixabay photo.

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Pollen feeders for honey bees

I was recently reminded of pollen feeders when I received a photo from Tammy Sill in Rhode Island. She said of her bees, “They roll in it like dogs on dead fish!!!” I have to agree. A good and plentiful source of autumn pollen will cause to bees to frolic as if they died and went to pollen heaven.

tammy-sill-bees in pollen
Honey bees frolic in a pollen feeder. © Tammy Sill.

Tammy’s photo reminded that another beekeeper, Naomi Price of central Oregon, has been experimenting with pollen feeding for a couple of years. She says that watching honey bees collect pollen from a feeder is an education in itself.

Feeding pollen in Oregon

Naomi and her husband had been worried about the fall supply of pollen because central Oregon’s weather pattern changed over the last few years. “We have had warmer than normal autumns that have little to offer foraging honey bees, hence they use up their valuable stores.”

She opted to purchase two pounds of bee-collected pollen from a highly-recommended local source. They ground the pellets into a powder and fed it back to the bees in an inexpensive homemade container. “It was more important that the bees be given the protein immediately rather than to worry about the human eye appeal of the pollen feeder,” she said of the plastic feeder. But the design worked perfectly and they continue to use it.

The main drawback was the expense of the pollen. “Oh well,” she said of the money. “The education was worth every penny spent for a good cause…Watching the honey bee carrying pollen is every beekeeper’s ah-ha moment.”

It turns out that the bees really packed it away. “My long hives usually store 2½ frames of pollen,” she said. “However, this extra pollen pushed the storage to 4+ frames.”

A simple pollen feeder

The following photos provided by Naomi and Larry, explain their ingenious system.

Bee-collected pollen
I started with two pounds of pollen from a reliable source.
Pollen in coffee grinder
It is best to grind small amounts of pollen pellets to produce dust that honey bees can forage. Here we used a coffee grinder.
2 liter plasic bottle
Select a container with a detachable and secure lid such as this two-liter plastic bottle.
Bottom cut from bottle
Cut out the bottom of the container to be used as the entrance and exit. Blue tape protects the rough-cut edges and presents a flower bull’s eye to the honey bee.
Bottle wrapped in tape.
The container needs to have daylight blocked so the honey bees can find the exit.
Drilling hole in tree truck
Larry used a screw to secure the container’s cap to a Juniper, upwind of the hive. Remember, honey bees usually fly into the wind because a slight breeze brings them fragrant forage information.
Installing feeder
The container can then be screwed into the lid. This container gives the pollen protection against wind and unexpected rain.
Filling the feeder
The container is loaded with a GENEROUS amount of dust. Remember, pollen is of no value to the honey bees if it is sitting on your refrigerator’s shelf.
Bees enjoying the pollen
We removed the feeder at night and brought it into the house to prevent moisture absorption by the pollen. We re-ground any dust left in the feeder and added it back the next morning. Our bees consumed 1# in three days. Most hives were bringing in three colors of pollen plus the offered pollen dust.
The second year we used the same type of container because they are easy to put up and take down. However, we added color to the outside instead of tape. We found the most important thing was to install the feeders upwind of the hives.

My own experiment was a “cat”astrophe

After reading these accounts from Naomi and Tammy, I was eager to set up my own experiment. So last week I placed three containers on the picnic table. One contained only pollen substitute, one contained a mixture of trapped pollen and pollen substitute, and the third contained only trapped pollen.

Once I was satisfied with my mixtures, I went to look for some tools. When I returned about five minutes later, the bowl of plain pollen substitute was empty. “What the?” I said aloud. Then I saw my cat doing this thing with her tongue. She was sticking it way out and scraping it against her teeth. Tongue, whiskers, and nose were dusted yellow and I thought she was going to choke to death. Who knew pollen substitute was such a yummy treat?

Honey Bee Suite