The case of hive #5

Our hive R5 which in 2018 had achieved a beautiful acacia honeydew does not seem very successful in 2019. While during inspections it seemed to develop well, the results are clear: 4.9kg against 15.8kg produced last year. The daily detail is given below:

The hasty beekeeper would attribute this fall in production to a honeydew lack, or to a queen in decline. “It worked well last year and must go down this year,” he (or she) would say.

That said, let’s see what the data says.

First of all, the state of brood

Our hive has excellent vitality, it displays a brood temperature at 35 °C ultra-constant all along April. Without inspecting it we can assure that it has at least 4 frames of beautiful brood. There was no swarm either during the period.

  • No, the queen is not declining.

Next, compare with peers

We are fortunate to have two other hives equipped with sensors in an apiary B just 2.6km as the crow flies. Hives R17 and R26 also have a fully developed brood like the R5 : We can compare these three colonies together and notice that finally, R17 and R26 are much better: + 7.2kg and + 10.5kg respectively.

Although the levels are different, the daily trends are quite similar between the three hives (see below) with red days and rather green days (they must all subscribe to Waze for bees?).

  • No, there’s no honeydew defect

So far, we can rule out as possible causes : 1/ aging queen and 2/ lack of resources.

What about the weather?

Normally the weather should not be the cause either. The two apiaries are very close and at this level the climatic conditions are identical. However, … let’s look at the maximum daily temperatures in each of the apiaries:

Very clearly, apiary A in which R5 is located is in a cooler environment than apiary B.

The average maximum temperature in April 2019 is 18.2°C in A and 21.2°C in B. A three degrees gap that seems to make all the difference.

The 20.5°C reached in 2018 on apiary A, seems to corroborate the hypothesis that the key parameter of our analysis is the sun exposure of the apiary. Indeed, it turns out that apiary A is in a wood under a cover of acacia plant, while apiary B is also in woodland but in the middle of a clearing.

Concluding remarks

Finally, the sun exposure of the apiary was at the origin of the production decrease of the hive 5. The bees were present, the resources and the weather too. But not the sunshine. In average April 2019 was 2°C cooler than April 2018 and this difference in local maximum average temperature had a strong impact in this apiary.

Apiary A

Apiary B