Fig. 2. Frequency distribution (%) of all the food-unloading events of different durations recorded in the constant series (each trophallaxis lasting more than 4 s was considered as an experimental unit). Data from 32 bees. Results are shown for each of the two different flow rates of sugar solution offered at the GF (grey bars, 3 µl min^-1; open bars, 90 µl min^-1).