Hive weight

Hive weight

The weight of a hive, or more precisely, the weight of the bees and honey it contains, and their rate of change compared to the weights and changes of other colonies nearby, may be the single most informative measurement one can obtain with colony monitoring technology.

A precise hive weight supplants the time-honored technique of “hefting the hive” to estimate its winter stores, and will provide usable information all year round.

The general questions that a hive scale can address are: Is the weight of this colony within the expected range, and is the weight changing at the expected rate, for a healthy, productive colony in this place, at this time?

More specifically, hive weight changes will (as the Arnia website notes) indicate the beginning and end of the nectar flow, identify when the honey supers are full, identify when winter feeding is required, indicate swarming and robbing event, and changes in colony strength and productivity.

Hive weight may be monitored several ways, and even a manually operated mechanical scale can provide valuable scientific data, see, for example:  honeybeenet.gsfc.nasa.gov

 


Hive scales

A hive scale is a scale designed specifically for weighing a beehive and the bees and honey it contains. There are a number of hive scales available, and a YouTube search will reveal that many beekeepers have their own methods of using scales to weigh their hives.

Scale attributes of interest to beekeepers include:

  • Mechanical or electronic
  • Placed temporarily or permanently
  • Manual or automatic
  • Read remotely or locally

Mechanical or electronic

Hive scales may be mechanical or electronic. Mechanical scales use a balance beam or a spring to weigh the hive, and these are the most economical way to begin weighing one’s hives. Electronic scales use one or more load cells to weigh the hive. Electronic scales require at least a small battery for their operation.

Electronic hive scales are more convenient, though more expensive, than mechanical ones. While the price of electronics, in general, falls rapidly over time, the weighing element of an electronic scale, the load cell, is temperature-sensitive, and each load cell must be temperature-compensated individually at the factory, which keeps the price high. Some electronic hive scale vendors try to reduce the overall cost of their scales by using fewer load cells in the scale. For example, instead of using four load cells, one at each corner of the hive, they may use two—both at one end of the hive, and assume the overall weight is twice the measured weight.

An exception to the need for temperature-compensated load cells can be made for electronic scales that are normally off and are turned on before each reading is taken. Turning on the scale zeros it at the current temperature, so the expensive temperature compensation of the load cell is not needed.

Placed temporarily or permanently

The scale may be placed under the hive temporarily or permanently. A scale that can be moved from hive to hive can be used to weigh all the hives in an apiary, this is very useful for comparing colonies to each other, a significant benefit. Using such scales is labor intensive, though economical, and weighing tends to be done less frequently than with permanent scales. Temporary scales may require that a fixture be attached permanently to each hive to enable the scale to slip into place easily as it is moved from hive to hive. A scale that is placed permanently under a hive can be read frequently, e.g., hourly, or more often if desired, which can reveal detailed information about the colony. The price of scales may make it cost-prohibitive to install a scale under every hive in one’s apiary.

Manual or automatic

Manual scales require that the beekeeper be physically present for tasks such as turning on an electronic scale, adjusting a balance beam, taking readings, and moving the scale from hive to hive. In contrast, an automatic scale does not need beekeeper intervention to provide data.

Read remotely or locally

Some scales can be read remotely, i.e., over the internet; others must be read locally, that is, the beekeeper must be physically present. Locally read scales include mechanical scales with a balance point or a pointer on a dial, scales with an electronic display, and the scales that transmit data to one’s cellphone using Bluetooth. Remotely-read scales transmit data via the cellular data network or by satellite. Remotely-read scales require a power supply for transmitting their data, as well as a data store at each end, together with analysis and display capabilities.

Accuracy

All scales have some inherent inaccuracies. Typically, more expensive scales are more accurate. Inaccuracies in hive scales arise from several factors:

  1. Temperature changes: Scales are affected by temperature. The materials in the scale expand and contract with temperature changes and these affect the scales’ readings. Even temperature-compensated scales are affected somewhat by temperature. If you put a thermometer and a scale under an empty hive, you will see that the temperature and the weight changes are highly correlated.
  2. Humidity: the wood in a wooden beehive absorbs moisture from rain and humidity. In winter the hive may have snow or ice atop it as well. These factors change the scale’s readings; they are not errors, but they are not the part of the hive’s contents that the beekeeper is interested in.
  3. Scale position: Some hive scales lift or support the entire hive, others do not. Those that lift or support only half the hive generally assume that the hive’s contents are evenly distributed and that they are measuring half the hive’s weight. Though this is not precisely correct when, for example, a feeder is placed at one end of the hive, it is usually good enough.

In general, hive scale suppliers make a cost/benefit tradeoff, attempting to provide the most useful (vs most accurate) weight they can for a given price.

In general, more accurate weights coupled with more-frequent weighings enable more-detailed observations of colony behavior, such as orientation flights, swarming, robbing, nectar processing, etc. Data science techniques may even make it possible, someday soon, to distinguish the weight of the honey from the weight of the bees (and see the article by Meikle et.al., 2008, in References).

 


Manual, Locally-Read Hive Scales

Manual scales, read locally, form one major category of hive scale. These scales may be either mechanical or electronic, and may be placed under a hive either temporarily or permanently.

[1] One observation hive owner we know has set up his hive so that hefting one end of the hive lifts the hive off the scale; the scale is then turned on, and the hive lowered onto the scale for a reading.

An internet search on “beehive scale” will yield other, similar, manual hive scale designs.


Permanently Placed, Electronic, Automatic, Remotely Read Hive Scales

Permanently placed, electronic, automatic, remotely read hive scales form the other major category of hive scale. Their major advantage is that the beekeeper can see the hive’s weight from anywhere there is an internet connection. The ability to read the scale remotely requires that the scale be automatic, electronic, and permanently placed.

These scales typically take readings frequently and capture small changes in weight that indicate various colony activities such as the departure and return of foragers, nectar processing, etc. The readings are typically recorded locally and uploaded to a central point periodically, though certain events, such as a sudden large weight change, indicative of a hive being tipped over, or a swarm, may be transmitted to the beekeeper in real time. Remotely-read hive scales are typically part of a larger system of components that may include, for example, temperature, humidity, and audio sensors, communications technology, an analysis process, and some method of displaying the results graphically on a website.

Remotely-read hive scales systems are usually offered by commercial providers. Some are relatively long-established, others are still seeking crowd funding. Components for these systems are readily available and are not expensive (excepting temperature-compensated load cells), but assembling them into a reliable system requires professional programming skills and knowledge of the related hardware. Remotely-read hive scales typically have two operating costs, one is the cost of replacing their batteries, and the other is the cost of the communications system that transfers data to the internet.

Vendors of Remotely-Read Hive Scales

Remotely-read hive scales are offered by numerous vendors.

AMES Environmental Measurement Systems, a Slovenian company, offers the TCM 13 hive scale. The scale is reportedly used by members of the Slovenian Beekeepers Association: http://www.ames.si/eng/cat/products/tcm_13_measurement_station_for_honey_collection_control/l:2.

The US contact for AMES products is the Belfort Instrument Company in Baltimore, Maryland: http://belfortinstrument.com/products/ames-environmental-measurement-systems/

ARNIA, a UK company, offers a hive scale together with a suite of other sensors, including temperature, humidity, audio, hive movement, and weather. The Arnia system has a unit in each hive that sends data to a central gateway (battery powered) that, in turn, communicates with the internet using a cellular data link. The gateway transmits data from multiple hives, reducing the per-hive cost of monitoring. The data is transmitted daily and displayed on any internet-enabled device. Data can also be downloaded. Arnia has been monitoring hives since 2009 and now (2016) has hundreds of monitors in 25 different countries. http://www.arnia.co.uk/

Arnia users may elect to share their data with the Bee Informed partnership: https://beeinformed.org

See also numerous videos and related publications online.

Bee Label is a French system, with a hive scale and various other sensors including a light sensor, hive and exterior temperature and humidity sensors, atmospheric pressure, and a hive location tracker. The cellular data transmitter is battery powered and sends colony data to the user twice a day, or more frequently if desired. The data is analyzed and the display can be viewed by any internet-enabled device.
https://www.label-abeille.org/gb/content/34-le-label

Bee Certain Wireless Hive Monitoring, located in Oregon USA, offers a hive scale together with temperature and humidity sensors, both inside the hive and outside, in the apiary. Data is sent from each monitored hive to a system recorder (that runs on household current), which then sends the data by Wi-Fi to a computer or cell phone within range. Bee Certain is currently (2016) adding the capability to upload data to the cloud for further viewing and analysis together with the ability to download the data for your own analyses.

Bee Certain also offers a portable wireless hive scale enabling the weighing of all the hives in your apiary with a single scale.
http://bee-certain.com/

BeeWise was the first electronic remotely-monitored hive scale that Buckaroo Beekeeper found on the internet some years ago. It is still offered.
http://www.beewise.eu/

BroodMinder, a US company, offers a hive scale together with temperature and humidity sensors. The system offers the sensors in several packages, each best-suited for a specific location in the hive: under it (the scale), above the brood box (temperature), and above the honey super (temperature and humidity). The BroodMinder sensors send data to the BroodMinder app on your cell phone when you are nearby. There, you can view it on a chart, send it to a web site (beekeeping.io) for further chart viewing, or email the data to yourself and do your own analysis. A BroodMinder advertisement in Bee Culture, 2016, claimed 1000 in use, and a goal of 10,000 in use by the end of 2017.

BroodMinder will open-source the collected data (maintaining beekeepers’ personal privacy requirements, of course) in order to facilitate investigation into improved beekeeping methods.
http://broodminder.com/

B-ware system from Solutionbee, located in North Carolina, USA. The system monitors weight and outside temperature. A data collector (wi-fi, cellular data, or satellite) sends data from each monitored colony to the internet where it is stored, analyzed, and graphed. The data collector’s batteries can be recharged by solar cells. The graphs can be viewed on any internet-enabled device. Certain events (e.g., significant or rapid weight change) will issue a real-time notification to the beekeeper. Data can be downloaded in spreadsheet format. B-ware shares your data with the Bee Informed Partnership.
www.solutionbee.com

Hivemind, a New Zealand company, offers a hive scale together with a suite of products for remote sensing. Their hive strength monitor includes temperature and humidity sensors as well as an imagery-based bee counter. Focused primarily on colonies in remote areas, communications is via a satellite hub. Other instruments from Hivemind include a water level indicator, rain gauge, and GPS locator for security purposes.
http://hivemind.co.nz/

HiveTool: “HiveTool™ is a collection of readily available, off-the-shelf hardware and free, open source software that continuously monitors a beehive. Computerized hive monitors provide real time and historic data and graphs of weight, internal and ambient temperature, humidity, and light levels which give the beekeeper a noninvasive view into the hive. HiveTool won the 2015 Bayer Bee Care Community Leadership Award.”

http://hivetool.org

https://www.youtube.com/watch?v=1lSLKvKMz2U

https://www.youtube.com/watch?v=qsKHckMX0OU2015

Do-it-yourself (DIY) electronics: A Google search on “honey bee” and “Raspberry Pi” or “Arduino” will lead to numerous DIY colony monitoring projects. These projects are in various stages of development, from dream to demise, and reflect a varied degree of understanding of beekeepers’ informational needs. Most of these run a poor second to the HiveTool DIY monitoring system also listed here.

Melixa is an Italian company whose colony monitoring system consists of a hive scale, a bee counter, temperature (internal and external), and rain sensors. The sensor set includes an accelerometer which will indicate that a hive has been jostled or moved, and a GPS hive tracker to counter theft. Data is uploaded to the internet periodically where it is stored and analyzed and can be viewed with any internet-enabled device. Data can be downloaded for further analysis. A solar battery recharger is available.
http://melixa.eu

Wi-Fi Hive Scale, an Ohio, USA company, offers a hive scale with an exterior temperature sensor. The hive scale connects to the user’s home Wi-Fi system and transmits data to the internet hourly where it can be viewed with any internet-enabled device. Like some other hive scale vendors, this scale weighs one side of the hive and assumes the true weight is twice the measured weight.
http://www.wifihivescale.com


References

William G. Meikle, Brian G. Rector, Guy Mercadier, and Niels Holst. Within-day variation in continuous hive weight data as a measure of honey bee colony activity. Apidologie 39 (2008) 694–707. DOI: 10.1051/apido:2008055. Available online at: www.apidologie.org

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