Estimating the strength of a colony

Schätzen der Bienen

Over a comb surface area of 1dm2 there are an average of 130 bees. But when large numbers of bees enter the cells, we can count up to 400 of them. This must be borne in mind during the evaluation.

If an entire Dadant comb, including the frame, is densely occupied by a layer of bees, it contains around 1400 bees.

If the comb is only partially covered by the bees, imagine them clustered over a portion of the frame, and evaluate what proportion of the comb is thus occupied (for example, half of the comb). Next, calculate the number of bees based on the proportion of the comb entirely covered by bees (in the preceding example, half of 1400, i.e. 700).

The following table gives the surface area of the comb in dm2 and the number of bees per entirely covered frame for different types of combs:

Comb type Surface area of face of brood comb in dm2 Number of bees per face of brood comb
Dadant  11.3  1400 
Schweizer 9.3  1200 
Langstroth 8.8  1100 
Zander  8.1  1000 
Deutsch Normalmass  7.2  900

The online evaluation exercise lets you test your ability to determine the number of adult bees on a comb. The estimate is made to within about 50 bees. The aim is to achieve a margin of error of 5 to 10%, more or less. Note that the bees in the photos have been counted individually to supply the correct answer.