I received my BroodMinder “Health Telemetry Sensor” devices this past week. It was a good week to have temperature and humidity sensors, as it’s been colder here with some hard frosts overnight multiple days in a row. Mind you, this is Virginia, so it’s been warm with the bees flying in the afternoons. This weekend we’re expecting temperatures near 70 (21 C), so don’t feel too bad for me or the bees.

I thought I would share some initial experience with the device and some changes I’ve already made to the hives as a result of the readings.

If you haven’t seen the “buzz” on this: BroodMinder started as an Indiegogo campaign looking to raise $20,000 and sell at least 500 devices. The device records temperature and relative humidity, and is designed to sit on top of a Langstroth box. Knowing how warm and how wet the top of the hive is should provide a good indication of how the bees are doing, especially during winter months when the bees are hunkered down inside.

The campaign was successful, and you can still order the device from the Indiegogo site. The first devices shipped on time the week of December 1, as promised. Developing hardware, especially for a new idea, never quite goes as planned, so shipping on time is no small feat. According to the latest update from the team the domestic orders (in the U.S.) have shipped and the international shipments are on their way. I am still not sure how best to “winterize” my hives: what is the best opening size? should I insulate the top? is upper ventilation really needed? So I ordered two devices to gain some insight into how my Langstroth hives were doing. Excessive water vapor is said to be a prime killer of hives in the winter, so I was especially interested in seeing the humidity settings.

Installation

You can tell the BroodMinder team has experience with electronic devices. The packaging is clean and simple, the installation is a breeze, and everything “just worked.” The one snag was that Apple had not yet approved their mobile app, so I had to use a version made available via Apple’s TestFlight program. This week Apple approved the app so you can download it from the App Store.

My first device arrived on Saturday. I sent a note to support@broodminder.com in the morning and by mid-afternoon had installed the app via TestFlight on my iPhone. Sunday afternoon I placed the device on top of our Mars hive, as shown in the picture at the top of this post. The packaging has a small tab that sticks out the back so you can see the device id without opening the hive.

The app is very basic, but gets the job done (see the BroodMinder Support page for a description of the app). After I installed the device the numbers looked good: around 3:30 pm the temperature was 64 F and the relative humidity was 68%; around 4:30 pm these were 61 F and 74%. One drawback of the current setup is that you have to physically visit your hives to record the reading on your phone. Hopefully this can change in the future so you can access multiple data points during a single visit.

The app displays the current temperature and relative humidity readings, with the low, average, and high over the last two weeks shown in a smaller font. You can also export the data via email to analyze the data over time. As I said, the app gets the job done.

Results

That was the end of the good readings. The temperature readings were great: 50’s and 60’s during the day and as low as mid-40’s overnight. I suspect the cluster gets a bit tighter as the weather gets colder, and with a full medium of honey the sensor is further from the cluster and thus has a lower reading at night. During the warmth of the day the bees spread out more and the top of the hive heats up.

The relative humidity was another story. As you may recall, I assumed a screen on the bottom would vent the moisture well enough; and added insulation on top to ensure that any condensation that does occur would be on the walls and away from the bees.

At 7 pm that first evening the relative humidity (RH) reading was 92%, the same at 8 pm, and then at 10 pm it dropped to 85% RH. The next morning at 7 am it was down to 73% RH. I couldn’t find a lot of commentary online about what the humidity should be in a beehive, but this seemed high to me. A couple references indicated that in the summer the bees maintain a humidity in the low 70’s (I can’t seem to find these now, so no links to share for this).

My guess at the time was that as the temperature cooled and the bees formed a cluster, the drop in temperature (which raises RH levels) and the warming of the cluster (which raises moisture levels via respiration) caused condensation in the hive (hopefully on the walls, of course!). Water will condense at 100% humidity, so the high 90’s likely indicates that water was already forming somewhere at the top of the hive. The other possibility, of course, is that the reading was wrong, but I didn’t consider this at the time.

Not wanting to rely on a single data point, I checked the readings the following night. Once again the humidity was in the high 90’s and the reading at 10:30 pm is shown in the image: 98% RH. I was unsure what to do until I did some research on humidity in buildings. These sites mentioned that relative humidity over 80% tends to promote the growth of mold and mildew.

Ventilation

I really wasn’t interested in having mold and mildew in my hives, so it seemed time for some ventilation. Adding an opening at the top of a hive releases moisture; it also releases heat, which is why I was reluctant to add this. I had already purchased two shims with ventilation in mind. My inexperience made me worry about the consequences: would the bees get cold, would robbing bees find their way to the hive, or would wasps or other insects get inside the hive? So I had done nothing with them.

In fact, Fedor Lazutin talks about this trade-off in his book Keeping Bees With A Smile. He says very little air exchange is required for respiration, as sufficient oxygen transfer occurs even with a small bottom opening. Removing moisture requires either ventilation or water-absorbing material such as the decaying wood and leaves found at the base of natural bee hollows. Since the Russian winters are so miserably cold, Lazutin opts for placing absorbing material inside and at the base of his hives. He claims this works quite well, though he does mention that he cleans off the interior walls of his hives in the spring. In his scheme, the moisture is absorbed and more heat can be retained by avoiding top ventilation.

For myself, Tuesday morning I added a shim to each hive. My second BroodMinder arrived on Monday, so I added the new device and a shim to Jupiter as well.

Worked intervened here, as I had to travel to Michigan for the next couple days. I arrived home Thursday evening anxious to check the readings. After some time with the family, I visited the hives around 10 pm.

I was a little surprised to find that Jupiter had readings of 58 F and 85% RH, while Mars read 59 F and 92% RH. Go figure. Too late and too tired to do anything about it, I went to bed. I’m writing this Friday evening and the readings in both hives have been 100% for a few hours. Remember this is after adding ventilation, so either the hive is still damp at the top or the readings are incorrect.

Next Steps

As I mentioned, we are expecting a warm weekend: the forecast now calls for temperatures near 70 F (21 C) as I post this Saturday morning. I’m reluctant to open up the hives yet again, though will make sure the bees are flying and check the bottom boards for mites and moisture.

I sent a note to BroodMinder to see if they have any thoughts. There was also a poster on beesource.com that reported some problems with some of the moisture sensors. I am going to assume the hives are okay, perhaps they were okay all along and the BroodMinder has been misreading the humidity. Knowing the temperature is still useful, so will keep them in the hive and see how both the sensors and the bees behave in the coming months. Stay tuned.

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Our title is a play on the song Baby It’s Cold Outside, written by Frank Loesser in 1944. The song was reportedly written and sung as a duet by Loesser and his wife during evenings with friends. Later it was recorded as part of the movie Neptune’s Daughter in 1949, when the song was seen as taking a liberal stance for women since the guest decided to stay despite what others might think. In more recent years the song is seen less favorably due to the man’s insistence that the woman stay despite her repeated refusals. I’m not sure it is fair to apply today’s standards to a 70-year-old song, and a recent article challenges the negative commentary about this song.

Now that we’re due for a few days of warm weather, the title doesn’t seem so appropriate. Perhaps I should use “Hey-bee, it will be cold outside again soon.” The perils of writing a post over multiple days of changing temperatures, I suppose. Stay warm out there.