Liebefeld Estimation Method
Lexikon
The Liebefeld method is a standardized procedure for assessing the strength of a bee colony much more accurately than by simply counting occupied spaces between the combs.
The Liebefeld method is a standardized procedure for assessing the strength of a bee colony much more accurately than by simply counting occupied spaces between the combs. It goes back to work by the researcher Jeffree in the 1950s and was developed further at the beginning of the 1970s by Hans Wille and Luzio Gerig at the Swiss Bee Research Centre in Liebefeld near Bern, today's bee research group of Agroscope. There it is still used for the scientific observation of colony development over the season.
When it is applied, each side of each comb is assessed individually. For the bees, you estimate what share of the area the bees actually present would occupy if they were mentally pushed together, in steps of quarters up to the full comb side. For brood and stores, a frame divided into square decimeters by strings is used, or alternatively a tape measure, to record the area of open brood, capped brood, and food stores. From these areas, the number of bees and the number of brood cells are then calculated using fixed conversion factors.
The conversion is based on the fact that a fully occupied comb side carries a different number of bees depending on the frame size: around 1,200 for the Swiss frame, around 1,400 for Dadant, around 1,000 for Zander, around 1,100 for Langstroth, and around 900 bees for the German Normal Measure. On one square decimeter of densely occupied comb area, an average of about 130 bees and about 400 brood cells are assumed.
In practice the Liebefeld method is used above all where accurate monitoring that remains comparable over a longer period is more important than a quick assessment, for example in bee research or when observing colony development over the course of the year. A check on two colonies over an entire season showed very good agreement between the estimates and actual weighing and planimetry measurements, while open brood is somewhat harder to estimate exactly than the clearly visible capped brood because its areas are less easy to see.
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