MONITORING HONEY BEES USING CAT® THERMAL IMAGING TECHNOLOGY
Name: Matt Newell
Hazards of the job: Bee stings!
Favourite App: BeeBook, a hive database. Open Office to keep Excel spreadsheets up to date on the go, the Met Office forecasting app, and the thermal imaging camera.
Phone for the job: My Cat s60. I use the thermal imaging function every day to locate swarms hidden in trees, nests behind fascia boards and to monitor winter activity when it’s too cold to open the hive. The screen is large and easy to operate when wearing gloves.
Why did I become a beekeeper?: I think there is something fascinating about the hive and bees. A system that interacts with the surrounding landscape, collecting honey in return for pollination, and the way humans can in turn interact with this. I particularly like breeding queen bees and selecting attributes such as disease resistance and honey production.
For the benefit of those without a working knowledge of honey bees, I’ll begin with some background information. When the temperature outside is 8°C or below outside, honey bees cluster in an approximate shape and size of a rugby ball. To generate heat they vibrate their wing muscles and rub against each other. When young bees (brood) are being reared during the first cooler months of the year, the cluster must work hard to maintain a steady temperature between 34.5 – 36.7 °C inside the cluster whatever the temperatures outside. In this state and given the right insulation, they have been shown to be able to survive down to temperatures of -40 degrees centigrade, and overwinter successfully in hives buried in deep snow.
As bees overwinter in the cluster, they consume their honey gathered from the previous summer. They use this stored honey at the time of year when there are very few flowers to gather nectar from. As can be imagined, cold and damp conditions in the brood box can be incredibly detrimental to hive health, especially when the bees are doing all they can to keep the temperatures stable as the thermometer plummets outside. Cold is especially damaging to brood and can kill vulnerable larvae instantly, the so called “chilled brood” effect. When spring does arrive, this means these first foragers will be missing and the hive will struggle to capitalise on the short season of abundant nectar to prepare for next winter.
The picture below shows two hives side by side. The left-hand side is a strong hive with a cluster that is giving a good heat signal. The right-hand side was a weaker hive going into winter after failing to build up to the size required and as such it is a weaker signal.
I was mentored by an old beekeeper whose winter mantra was “keep their tails cool and their heads warm” and there’s a lot of sense in that. Using the Cat S60 it is very easy to see areas of heat loss during the cold weather. This can be dealt with by giving insulation to the roof, something I did this year for the first time after seeing a big heat signal on my Cat S60. Less heat lost means less honey consumed and a more successful spring build-up. The economic benefits to both bee and beekeeper are obvious.
“[…] the Cat S60 is a useful tool to see the amount of heat generated and dissipated by a hive of bees, and from where.”
However, adequate ventilation is also a key aspect. We have all been in a stuffy room and it isn’t particularly pleasant. To facilitate convection and heat transfer from where the heat is generated to where it is required there must be adequate hive ventilation. Furthermore, the consumption of honey produces water vapour as a by-product. If this is allowed to accumulate, it can collect on the inner cover and drip into the cluster which will lead to damp conditions, the prevalence of disease and very unhappy, short- lived bees. So the Cat S60 is a useful tool to see the amount of heat generated and dissipated by a hive of bees, and from where.
This image shows the loss of heat through convection. The hive on the left has a ventilated floor made mostly of fine mesh. The hive on the right has a solid floor and less ventilation meaning the bees have to work harder to remove the warm but damp air from the broodnest.
The traditional method to see the amount of honey stored is by lifting the hive and estimating the amount of honey stored in the combs. Beekeepers call this “hefting”. Whilst this shows the amount of honey in the hive from the weight, this will not show the location of either the stores or the cluster of overwintering bees. If they are not near each other starvation will still occur.
What I have been looking for using the Cat S60 smartphone is the position of the cluster during the colder months of the year. This has been done in scientific studies in the past, but instead of using the integrated FLIR camera, it was performed using cyanide gas to kill the bees whilst clustered and to examine the location of the clusters in relation to the stores, and the amount of brood raised. Quite a distressing thought. Using the thermal imaging technology, I am able to locate the clusters of bees inside the hive through the wall without any other interaction with the bees at all. Because stored honey is always stored above the cluster in a large arc, if I can see a large cluster of bees right at the top of the hive, I know they are probably hungry and are running out of stores, and will be unable to maintain the temperature in the hive. They will require urgent attention to avert colony loss.
“Using the thermal imaging technology, I am able to locate the clusters of bees inside the hive through the wall without any other interaction with the bees at all.”
The size of the heat signal will also inform management techniques. Often a weaker heat signal shows there is the possibility of a smaller, colder cluster and therefore the inability to raise brood.
However, this is not always the case. By comparing the behaviour of several hives of a fairly uniform weight and strength, and using the combined information of the size and heat signal of a cluster and comparing it to the outside temperature, it can show some very interesting aspects of hive behaviour without having to remove the roof, disturb the cluster, or get stung!