4.1.4. The use of the data from an electronic scale
Very often it is difficult to judge what is going on in honey bee colonies. The hive scale is an important tool and gives a good assessment if food consumption has been high over a longer period and whether there is a need for feeding. In most countries, it is important to know how big the winter storage is since it will tell if spring feeding of carbohydrates is needed. In addition, it gives a very good assessment of periods without any flow in the summertime and hence can warn of starvation danger. Finally, it gives a very good evaluation of how intense the nectar flow is, in other words, if there is a need to provide the colonies with additional supers. Commercial beekeepers use hive scales to save unnecessary visits to the apiary when they do long-distance migration. Examples are German commercial beekeepers having colonies for pollination of white clover in Denmark. With the scale, such migration has become profitable, since the driven kilometres can be kept to a strict minimum. The German hive scale system (see Table 12) is especially a warning system for the start of honeydew flow. It tends to start suddenly and can be massive. The scales also give very good information about when the nectar flow stops. In Denmark, information from the honey meter has shown that the main nectar flow stops, in general, earlier than the beekeepers expect. Some Danish beekeepers make all their varroa treatments according to the figures of the honey meter with the positive result of earlier and therefore more efficient varroa summer treatments.
Measuring brood temperature indicates when there is no brood in the colonies. This is the optimal time of the year for varroa-treatment with oxalic acid. But note that since there is only one temperature sensor, one has to ensure correct sensor placement in the centre of the winter cluster. With scales, obtaining an indication of colony swarming through a decrease in its weight (Meikle et al., 2008) is also possible. A necessary requirement for accurate measurements and predictions is to monitor good/well running colonies on the scales.
Having colonies on hive scales is providing very important complementary data on colonies used for experiments. The disadvantage of the system is that the figure of increasing/decreasing bees and brood in the colonies are influenced by variation in food stores. A very nice experiment is that of Meikle et al. (2008) who used precise bench scales (± 10 grams) that measured every hour. They weighed separately the bees, brood and food, showing that the main part (76%) of the colony weight throughout 2005 was food. However using scales with a precision of 10 grams in the field entails large errors due to the accumulation of rain or even due to wind pressure on the hive body. It is important to use Styrofoam boxes, since wooden boxes absorb moisture and thereby bias weight measurements. In wintertime, it is important to have the colonies protected from snow and ice in order to have reliable day to day measurements.
Procedure to follow when using a hive scale (Capaz scale)
- Place the hive scale on a levelled platform – to protect against moisture from the ground.
- Connect all plugs. Test for cell phone connection according to manual.
- Secure a protection cover for the scale, protecting against debris from the colony, from precipitation, driving rain etc.
- Check battery charge regularly – recharge at least every spring and fall.
- Keep all plugs clean and dry – otherwise rust problems will arise.
- Use Styrofoam boxes, since wooden boxes will absorb moisture.
- Ensure that water runs of the hive cover, otherwise water can accumulate or be absorbed, biasing results. In countries experiencing snowfall, scales and colonies should be protected in a house, external cover or shed. Otherwise winter measurements will be biased.
- If using the Capaz brood chamber sensor, ensure that the sensor is placed in the centre of the winter cluster during winter.
- Refer to scale manuals for data downloading.
- Download the data regularly and make
backups, since it is an enormous amount of data that is collected.