Using hive scales to estimate the strength and health of bee colonies
In this tutorial, we explain how you can compare weight curves from the same apiary to:
- estimate the strength of colonies during wintering,
- detect failing hives during honey flow.
These analyses are only possible by comparing the curves of different hives in the same apiary with each other. If you only have the curve of a single hive on a scale you cannot make this type of analysis.
If you want to have this tool at home, you must equip your hives with:
➡ A BEESCALE4 system with 4 scales
Compare weight curves to estimate colony strength during wintering
1 - Estimating colony strengths in wintering
During wintering, the colonies lose weight in a very linear fashion. This loss is proportional to the number of mouths to feed. It is between 1.5 kg/month and 2.5 kg/month -
To compare your colonies with each other, display the curves over a 21-day period. Click at the beginning of the period, click at the end of the period. The difference is displayed, you can classify your colonies by strength according to the quantities consumed.
2 - Detecting a dying hive
For the colonies that are weakening, the curve flattens progressively. Indeed, the number of bees decreasing their consumption is less and less important. With a bit of practice, you will easily detect the curves which "flatten" and therefore the colonies which are disappearing. On the graph this is the case on the black curve.
A consumption of 2.5 kg/month corresponds to a colony occupying 6 to 7 frames in wintering. 1,5Kg per month corresponds to a colony on 4 to 5 frames.
In May when the colonies occupy 1 Dadant body and a rise, they can consume more than 10Kg/mois.
Comparing weight curves to detect a failing hive
1 - weak colony (queen failing or having swarmed)
The weak colony has fewer foragers than a normally developed colony. It will naturally harvest less than a normal colony. This is a very frequent occurrence and the beekeeper can make a direct link between what he sees in the population size and the harvest curve. In the above example, the hive swarms and then does not harvest during the June honeyflow, but instead it recovers and harvests during the July honeyflow.
2 - strong but ragged colony
Loose colonies may in some cases be very strong and show no really obvious signs of disease. The beekeeper will only be able to detect an abnormality if he notices that, despite the appearance of a good colony, it is not harvesting sufficiently compared to the other colonies in the apiary. This is the case of the curve presented above on the left example.
You can use the brood sensors in the hive to know in real time the humidity of the hive and thus indirectly that of the honey. For the moment, there is no study allowing to establish an exact correspondence between the real humidity of the honey and that of the atmosphere of the hive. With experience you will establish your own gauge.
Detecting an abnormality due to an external factor
If you have a good homogeneity in terms of genetic quality and age of your queens as well as a sufficiently melliferous environment (average at 25kg without any notable honeydew holes), you can expect a mostly homogeneous behaviour of your hives.
If this behaviour is abnormally heterogeneous then you may suspect an external negative factor: varroa, poor quality food bolus, lack of water, high swarming rate.
Of course, this type of analysis is only worthwhile if you are an experienced beekeeper with well-established practices.