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Data Interpretation

In this section, we present some initial findings from Theo's hives. We are still very much in the learning mode and will appreciate your observations shared on the BroodMinder forum at

These reports were written in the summer of 2016. You can look directly at the data in by looking in the Claypoint apiary. This is available as a demo apiary.

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Hive Weight Profiles

By Ray Walker, May 2016

Hive weight trend charts contain repetitive shapes or profiles, depending on the season, floral resources, rainfall, temperature, humidity and other variables. By studying weight profiles, beekeepers can learn more about their apiary's foraging resources, colony's status, health and performance. Daily, weekly and monthly profiles of each colony can be compared with "typical" weight profiles for an apiary's local environment (based on historical scale trend data).

Hive weight trend data can be used to estimate bee populations, nectar collection and consumption rates, accumulated foraging hours, foraging performance and other colony characteristics.

During the past 3 years, I've been applying a variety of electronic hive scale systems to study and compile a library of "typical" weight profiles for my backyard apiary. Since the end of April, I've been using a BroodMinder hive scale prototype.

Monthly Profiles

The main nectar flows in northern Delaware occur during the months of May and June (typically about 50 days duration). For an overwintered nucleus colony to exploit the main flow, it's population must increase rapidly in March and April โ€“ peaking just before the flow begins.

Weather conditions have a big impact on how well the colony's foraging population collects nectar from the variety of available blooms. Flying conditions (rain, wind, temperature, humidity, etc.) must be ideal when blooms are pervasive to maximize monthly foraging rate. By examining the shapes of the monthly profiles and observing when specific blooms occur, the major nectar resources for the apiary location can be determined (and compared year-to-year).

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Monthly Trend Chart

Early May's cooler temperatures (50-60's) and rain limited foraging rates.

Increased daytime temperatures (70-80's) and less rainfall improved flying conditions during the end of the month. Best foraging rates were obtained when the bloom's nectary had warm day-time and cool night-time temperature cycles. The colony foraged ~90 pounds of nectar in the month (~3 pounds per day). Black locust and tulip-tree were both blooming during the end of May.

Weekly Profiles

By charting the week of maximum nectar flow, a series of repetitive profiles show routine day-time weight gains as nectar is collected then night-time weight losses as nectar is evaporated and the colony is consumes nectar. By comparing this season's maximum weekly profile to previous season's maximum weekly profile, a relative comparison of colony foraging performance is obtained.

Weekly profiles of maximum weight gains can be added to a library of trend charts for evaluating an apiary's foraging capability to other apiary location's capability.

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Weekly Trend Chart

Increased average temperature cycles with wider spreads in day & night temperatures as well as stable/lowest humidity produced the maximum nectar flow.

The average foraging rate for the best four days was about 10 pounds per day. This rate compares to previous year's foraging rates. However, the maximum nectar flow duration varies from year to year.

Daily Profiles

By charting the day(s) of maximum nectar flow, the typical daily routine of the colony can be studied. The colony's initial foraging flights occur at the same time each morning. Several foraging "missions" can be observed as the weight increases at various rates (depending on which blooms are available at different times of the day). Towards evening, the foraging force returns to the hive and the weight peaks for the day. During the night-time, moisture from the nectar is evaporated and bees consume nectar.

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Daily Trend Chart

Daily profiles indicate which portions of the day-time hours the foragers are most active โ€“ providing the beekeeper insight when hive inspections would be most disruptive.

Swarm Detection with a BroodMinder TH in a Top Bar Hive

By Theo Hartmann, June 2016

This is a case where a BroodMinder TH device in a top bar hive was helpful in tracking the progress of the

colony in a remote hive. The BroodMinder Temperature and Humidity Device was installed in a recess in the end board.

The colony was installed from a swarm into this hive and then moved to a remote location. My remote agent was kind enough to obtain the data from the BM device on a daily basis and upload it to

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Below is a screen shot from showing the entire time period since the colony was in this hive:

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Because of the nature of this hive and the location of the device at one end of the hive, it is not expected that the measured hive temperature stays at one level as it is the case in a Langstroth hive. What caught my eye were the last two days where the temperature dropped to the lowest level since the bees were introduced into this hive.

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Granted, ambient temperature dropped, too but going back to May 16th, ambient temperatures were lower back then at the same or higher hive temperatures. I concluded from this that the colony had swarmed because lower temperature means less heat generated means less bees inside the hive to generate heat and keep the hive temperature at a higher level at night. I went there for an inspection and this is what I found:

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Few bees on the comb and two open swarm cells at the bottom of two combs.

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Clearly, a lot of bees have moved out to find a home elsewhere. This is not necessarily a bad thing because the bees which are left behind have ample resources in the hive (pollen, nectar, honey). The natural process of queen replacement has already begun since two new queens have hatched as evident from the open swarm cells. Also, the mite count in this hive will drop since the brood cycle has been interrupted.

The BroodMinder TH device together with a remote agent and proved to be effective tools to monitor this hive in a remote location.

Avoiding Excessive Heat in the Hive During Summer Months

By Theo Hartmann, June 2016

This document describes findings on two hives which were started this spring. One was from package and the other one was a small swarm. Both colonies were introduced into Langstroth 8-frame deep box hives and were developing at a more on less identical pace and both hives were expanded to two brood boxes per hive pretty quickly. The BroodMinder Temperature and Humidity devices (TH) were placed on top of the upper brood box. There is no super above that, just the inner and outer covers. Temperature peaks started to appear on June 6th at times when the mid-day sun was hitting the outer cover of the hives as can be seen on the chart below.

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The peaks would reach 100+F almost every day between June 6th and June 15th. At times, these temperatures were 20F above ambient temperature and clearly, this must have put unnecessary stress on the bees. The hives essentially became greenhouses. This was surprising because both hives have screened bottom boards and screened and ventilated inner covers for the summer months. A 2" high density Styrofoam insulation was placed on top of the screened and ventilated inner cover on the starter hives on June 15th. This resulted in elimination of the temperature peaks.

For comparison, here is a temperature profile from a mature hive with honey supers:

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No peaks and a more mellow change in temperature.

These same to charts are shown again below and a few additional things can be concluded from them:

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Notice that the difference between the hive temperature and ambient temperature generally is smaller for the starter hive (top) compared to the established hive (bottom). The reason is the number of bees in the hive. The starter colony is affected much more by changes in ambient temperature than the established colony.

The more gradual change in temperature on the established hive can be attributed to the fact that there are two honey supers above the TH device. These supers shield the brood nest from the temperature peaks seen in the hive which does not have any supers. The very top of the hive with the supers sees the same temperature peaks observed in the starter hives but these peaks never make it down to the TH device.

This discovery and subsequent corrective action was only possible because:

  • BroodMinder TH devices are installed
  • Data are collected on an hourly interval
  • Plots of the data available instantly on
  • Local weather data were added by for reference

The cost to do this analysis is the purchase price of the BroodMinder device, nothing more. All the other data and analysis tools are available to BroodMinder users for free.

Detection of Cluster/Queen Movement and Spring Brood Buildup

By Theo Hartmann, June 2016

This example shows how multiple BroodMinder devices in the same hive can be used to detect a number of things without actually opening the hive for physical inspection.

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The setup is a 8-frame Langstorth hive with two deep brood boxes, screened (but closed) bottom board, sugar board with top entrance above the top box, insulated inner cover and outer cover.

This was the configuration of the hive going into the winter. One BroodMinder TH device was installed between the top brood box and the sugar board and second BroodMinder T device was installed between the two brood boxes. was still in it's infancy at the time the test went underway and for this reason; another BroodMinder TH device was placed outside in a protected area to gather ambient conditions.

Here is an overview of the data collected. The green line represents the temperature above the top box, the red line the temperature of the bottom box and the dotted line is the ambient temperature.

  • Higher temperatures in the top box indicated that the cluster is up there feeding on honey stores and sugar.

  • Temperatures equalize between the boxes but are not high enough for brood to develop.

  • Both boxes are getting warmer which could be a sign that the queen started lying, potentially in both boxes.

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This chart is broken down in sections for a closer look at the data and corresponding analysis.

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Here a switch happens and the bottom box begins to get many bees up there. The bottom box is now kept at 90+F. Perfect conditions for brood to develop. The top box follows the ambient temperature swings. Not warmer than the top indication that the queen has moved down into the lower box.

These data indicate a healthy hive and a subsequent inspection revealed that this is in fact the case and the colony is ready for the nectar flow.

Pull the Supers When the Dearth Hits

By Theo Hartmann, July 2016

Every spring it is a pleasure for beekeepers to watch the bees going on their daily excursions and bringing back pollen and nectar. As we all know, this is to both feed the larva and also to produce honey stores for the next winter for the colony to feed on. Having the hive weight available is a great help in making the decision when to harvest honey from the hive. There is a spring nectar flow which can produce large amounts of honey in a short time as seen in the charts copied from the mobile app below. The hive weight increased rapidly during the second part of May.

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There are the daily ripples caused by the bees bringing in nectar during the day causing weight increase. Then, during the night, bees are busy reducing the water content and the hive weight decreases. There also are the larger jumps where the beekeeper added or removed frames or supers.

Longer term, the weight increase clearly ceased middle of June. The hive on the right even shows a decreasing trend in hive weight. This is a clear sign that the dearth has set in and there is not enough natural food available. The bees begin to consume the honey stores or ever worse, robbers grab what they can get. Below is a chart of such a situation.

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The hive weighed a whopping 185lb when the dearth hit. Then, on June 28th the weight started to drop like a rock. It stabilized at about 155lb the next night. 30lb lost. The following day, again massive weight loss took place down to 133lb, another 22lb lost. The weight loss continued the following day until the beekeeper removed the honey supers and got the hive under control. The robbers knew exactly what they were doing after they discovered the venerable hive. Take out what we can the first day, take a rest and then go back for more, day after day. There was no other hive with a scale nearby otherwise we would probably see where the loot went!

The above makes it clear that honey supers should be removed when the dearth hits, latest when the hive weight starts to decline. The BroodMinder-W scale is of great help to time the removal of the honey super(s). This will not only mitigate the robbing risk but also increases the bee density in the hive and the ability for the colony to defend their hive. It is also the time to install an entrance reducer and/or screens and close off any top entrances. With these measures, the robbing risk is minimized.

Here is an additional tip for BroodMinder-W users:

Removal of a full honey super results in a reduction of the hive weight by 40-60lbs which is a significant portion of the total hive weight. This is an excellent opportunity to get information for adjustment of the hive scale factor in the mobile app. Therefore, weigh everything you have removed from the hive as accurate as you can with a bathroom scale, a postal scale etc. and record it. Visit the BroodMinder forum for advice on how to adjust the hive scale factor.

Getting back to the dearth, food is scarce for the bees during the dearth period and they may require supplemental feeding. Knowing the hive weight of established colonies is essential to determine if it is necessary or not. First year colonies require feeding irrespective of the hive weight.

On established colonies I would recommend to start feeding if the hive weight starts to drop. This will reduce stress in the colony since the food is readily available inside the hive. This is substitute food for the lack of nectar out there. Stop feeding when the hive weight increases. The bees have found another nectar flow.

When feeding in the summer I use 2:1 Sugar syrup. My thought is that a 1:1 is good for spring to get the queen thinking that there is a nectar flow and she will lay more eggs. In the summer and after the spring nectar flow is over, the bees are busy making honey out of the nectar they collected. During this process, the bees remove vast amounts of water from the honey before they can apply their seal of approval and cap the cells with an airtight wax cap. The last thing the beekeeper wants to do is give them more water. So, thicker syrup is better in the heat of the summer. Hint: Add 2 tbsp per gallon (1/2 tbsp per quart) of apple cider vinegar to the syrup. This lowers the PH to the level of honey and prevents black mold.

Promising Citizen Science Project Observations

By Theo Hartmann, August 2016

As an early adopter of the Citizen Science (CS) Project, I have seven hives set up in this configuration and data are collected on all of them on an hourly basis. This paper illustrates the power of this setup where multiple hives can be compared on an even basis to detect anomalies and define resulting actions.

True to their name, BroodMinder devices detect the presence of brood: The measured temperatures show that the bees hold the nest temperature at a constant 95-96ยฐF when good brood is present. The charts below show both, the superb job the bees are doing raising babies and also the quality of the BM devices showing exact temperatures.

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Using BroodMinder Data to Optimize Hive Preparation for Winter

By Theo Hartmann, October 2016

This is the time of year when beekeepers are preparing their hives for the winter season. There are a few essential steps which typically take place:

  1. Ensure adequate resource levels in the hives to be overwintered
  2. Ensure that each hive has a laying queen and the brood nest in the bottom box and resources around and above it.
  3. Consolidate weak hives for the winter and split them in the spring

Below are a few examples from my apiary showing how BroodMinder data help to plan the hive inspections and hive configuration changes to accomplish the above goals. The apiary discussed here has six active hives next to each other. Hive 2 is a control hive without bees. All hives are configured the same with two 8-frame deep boxes. Supers have been removed earlier and all colonies are fed with Boardman style entrance feeders. The combined weight of each hive hardware is just under 50lbs.

  1. Using Measured Hive Weight to Determine Resource Allocation

The goal is to have about 60lb of resources in each hive going into the winter. This consists of capped and uncapped honey, pollen and supplemental food as needed. The situation as found after the summer is as follows:

Hive # 1 3 4 5 6 7
Gross Weight lb 100 130 70 100 80 80
Hardware lb 50 50 50 50 50 50
Net Weight lb 50 80 20 50 30 30
Over/Under lb (10) 20 (40) (10) (30) (30)

Only hive 3 fulfills the 60lb resource requirement. All others need help. It was decided to remove some of the excess honey from hive 3 (4 frames) and put it in hive 4 (2 frames), hive 6 (1 frame) and hive 7 (1 frame). This resulted in this revised weight distribution:

Hive # 1 3 4 5 6 7
Gross Weight lb 100 110 85 100 85 90
Hardware lb 50 50 50 50 50 50
Net Weight lb 50 60 35 50 35 40
Over/Under lb (10) 0 (25) (10) (25) (20)

Most hives are still short of the 60lb resource goal.

  1. Using Brood Box Temperature to Detect Queen Presence and Brood Nest Location

Hive temperatures indicate that the queens have slowed down their laying rates, which is normal for this time of year.

Below is an example to show this condition. The bee colony kept both brood boxes at around 96F until the end of September. Then the bottom box dropped off followed by the upper one. This would indicate that the queen stopped laying in the bottom box first followed by the top one. Beekeepers who use Oxalic acid to reduce the Varroah mite count in their hives can use this temperature drop as a trigger to start treating their hives because from that point forward there will be a minimal number of capped brood cells in the hive.

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Taking a snapshot of the temperature levels before the queen laying rate started to decrease showed the following:

Hive # 1 3 4 5 6 7
Upper Temp F <90 <90 >90 <90 >90 <90
Lower Temp F <90 >90 >90 >90 <90 >90

This was around the beginning of October

90F was taken as a threshold to determine brood/queen presence. The hive inspections confirmed open brood presence in the boxes indicated in green above and no or very little capped brood in the boxes shown in red.

  1. Hive Reconfiguration and Consolidation

The following actions will be taken or were taken already:

  • Hive 1: Queenless hive. The two boxes will be combined with hives 4 and 6. Hive 1 will be closed for the winter.

  • Hive 3: No configuration change

  • Hive 4: Combine brood from both boxes to the bottom box. This creates a smaller brood location, easier to keep warm

  • Hive 5: No configuration change

  • Hive 6: Move brood to the bottom box

  • Hive 7: No configuration change

All live hives will get a 20lb sugar board with top entrance. This will take care of the missing resources. They also get a 2" Styrofoam hive top insulation. Bottom entrances will be reduced to ยพ" width, screened bottom boards will be closed and the Boardman entrance feeders will be removed.

Good night girls. Sleep well and see you in the spring!