Use hive scales and brood probes to track egg laying and achieve oxalic acid success

In this tutorial we explain how you can use the brood probes to follow the egg laying and make a success of your organic treatment with oxalic acid.

For this explanation we rely on the recording of the resumption of egg laying at the end of January.

If you want to have this tool at home you must equip your hives with the complete BEESCALE4 system as well as the weather and brood probes.

Having the right configuration

full multistage conguration
BEESCALE4 configuration with 4 brood probes and 1 external weather probe.

1 - The external probe, also called "Weather" probe

In the BEESCALE4 configuration, we propose a probe called "Weather". To interpret the brood curves, it is totally indispensable! Indeed this sensor is not intended to provide the weather conditions, but it is well intended to be an external reference to the hive.

Indeed, all the brood data are interpreted by analyzing the difference between the inside of the hive and the outside of the hive.

2 - The 4 brood probes

BEESCALE4 offers 4 brood probes, one per hive to be connected on each lane, it can be added very simply in addition to the scale using a Y-connection cable provided.

When working with brood probes, make sure they are always in the center of the cluster, otherwise your temperature and humidity measurements on brood will be distorted.

Reading and interpreting the brood chart

The graph of the data from this probe may seem a bit complex at first. If you take the time to decode it, it is very easy to read. It consists of 2 distinct graphs.
The first one concerns the temperatures and includes:
- the 4 brood temperatures
- the outside air temperature (in green on the graph, named: Ext.)
The second one is about humidity and includes:
- the 4 brood humidity measurements
- the outside air humidity measurement (in green on the graph, named: Ext.)
Only the comparison of the 4 humidity and temperature channels with the outside values will give you answers about the presence of brood or not.

Example of resumption of egg-laying at the beginning of February
(graph over 2 months)

1 - Recovery of the brood at the end of winter (beginning of February)

The graph below clearly shows a change in the temperature and humidity curves from the beginning of February. It can be seen that on days with good weather in January, the internal temperatures of the hives rose sharply, but the recovery did not take place until the temperature remained above 5°C for several days.

2 - stabilisation of temperatures between 30°C and 35°C

We can clearly see that from the beginning of February, temperatures stabilize suddenly between 30°C and 35°C. The P1-Black curve takes longer to reach 35°C. This probably means that the probe is not really in the center of the cluster and thus only partially benefits from the heating of the bees.

3 - humidity stabilization between 45% and 55%.

As with the temperature, it is clear that suddenly from the beginning of February the humidity stabilizes between 45% and 55%.

The visualization of the stabilization of the 2 values Temperature and Humidity, allows us to deduce that the oviposition resumed in these 4 hives at the beginning of February

Thephenomenon of regulation by the bees of the Temperature and Humidity in a fixed range is called HOMEOSTASY.

Successful BIO treatment with oxalic acid

The principle of the organic treatment consists of intervening twice:
- Once in the summer by blocking the egg laying voluntarily and diffusing dripping oxalic acid
- Once in the winter by using the natural egg laying blocker to make a second diffusion of oxalic acid by sublimation
These two treatments must be accompanied by a measurement of the infestation rate on the diaper to be sure of the level of varroa infestation.

1 - Intervening in summer

The principle of the summer intervention is to take advantage of the summer honeydew to lock the queen in a cage. The bigger the cage is, the less queen will be lost (the ideal being to block it on a whole frame where she can lay eggs). After three weeks, the queen is decanted and the bunch is sprinkled with oxalic acid. Monitoring the brood temperature is not fundamental but will go well with the monitoring of this operation.

2 - Intervening in winter

Unfortunately it is not possible to be satisfied with a single summer treatment. It is also necessary to carry out a sublimation of oxalic acid in winter (even 2 in some cases). At the end of October, position the brood probes in the center of the bunches and you will clearly see the egg laying stop. This means a progressive loss of homeostasis conditions. You will know when to intervene to be really out of brood at the time of the treatment and thus be efficient.

Devices that do not provide egg-laying status

If you wish to use other equipment than BEESCALE, it is possible but only the probes that are immersed in the center of the cluster can really give the exact temperature and humidity of the cluster. Indeed, the boxes and probes located ON and around the frames (number 1 on the picture below) are most of the year (and especially in winter) outside the cluster. If the temperature is not at 35°C we cannot deduce anything from this.

Probes for monitoring brood temperature

The Mellisphera / BroodMinder approach

Mellisphera proposes another approach which consists in defining a state of the colony from the measurement of the temperature on the TOP of the frames. This value will reach 35°C in high season when the hive will be at its peak of development and will fluctuate downwards out of season according to the size of the cluster and the outside temperature.

Melliphera has designed an algorithm based on this temperature which defines a colony strength. Assuming that the whole apiary is equipped, it is possible to compare the hives between them and to quickly detect the weaker than average hives (which need to be visited). If this approach does not give the exact temperature of the brood, it is nevertheless very interesting to have an instant global view of the apiary.

Probes to give an idea of the strength of the colony