Estimating Colony Strength
Lexikon
Colony strength means the approximate number of bees a colony comprises at a given point in time.
Colony strength means the approximate number of bees a colony comprises at a given point in time. Estimating it is one of the basic skills in beekeeping, because it shows whether a colony is strong enough for wintering, whether it tends to swarm, or whether it needs additional support such as feeding or uniting with another colony.
In practice, colony strength is often roughly estimated from the occupied spaces between the combs: you look down between the frames from above and count how many spaces are densely occupied by bees. As a rule of thumb, the values of the Liebefeld method are often used, according to which a fully occupied comb side in the Zander size carries around 1,000 bees, but in the Dadant size around 1,400 bees, because the comb area is larger there.
Colony strength varies considerably over the year. When the colony goes into winter in autumn, figures of roughly 5,000 to about 13,000 to 15,000 bees are considered the usual range, with considerably weaker colonies considered critical for wintering. In early summer, at the peak of colony development, strong colonies can comprise 25,000 to well over 40,000 bees. These ranges differ somewhat depending on the source and the bee breed, but agree well in order of magnitude.
A common beginner's mistake is to judge colony strength after a single, short inspection in cool weather. At low temperatures bees often sit more tightly together or in several layers on top of each other, so that the number of occupied spaces can underestimate the actual colony strength. An assessment in mild weather, when the bees are distributed more evenly over the combs, is more reliable.
Sources (3)
- Überprüfung der Schaetzmethode zur Ermittlung der Brutflaeche und der Anzahl Arbeiterinnen in freifliegenden Bienenvoelkern, Imdorf et al. 1987, Agroscope / Schweizerisches Zentrum für Bienenforschung
- Lehrgang zur Erfassung der Volksstärke, Imdorf & Gerig, Agroscope / Schweizerisches Zentrum fuer Bienenforschung
- Die Liebefelder Schätzmethode: Das Gefühl mit Verstand untermaürn, Schweizerische Bienen-Zeitung