Bumblebee’s preferences for continuous strings in different string-pulling experiments. Percentage of pulling connected strings compared with chance level (50%). Median, interquartile range and range are given. Boxes show the 25th percentile, 50th percentile (median), 75th percentile. The dashed line represent chance level (50%) and the circles indicate individual bees’ data points. *** indicates P< 0.001.

The number of total choices and bees that chose connected strings at first choice.

Duration of bumblebees attempting to pull the strings across experiments. Median, interquartile range and range are given. Boxes show the 25th percentile, 50th percentile (median), 75th percentile. Circles indicate individual bees’ data points. *** - P<0.001; ** - P<0.01; * - P<0.05.

Latency to the first choice in different experiments. Median, interquartile range and range are given. Boxes show the 25th percentile, 50th percentile (median), 75th percentile. Circles indicate individual bees’ data points. Different letters indicate significant differences (P<0.05).

Experimental apparatus and summary of training in different experiments. (A) The experimental setup consisted of a flight arena connected to a hive via a Perspex corridor. (B) Foraging bumblebees were number-tagged, and the marked bees were trained in a stepwise manner.

Schemes of eight string-pulling experiments. Bumblebees were trained and tested in different situations. Two flowers were placed under each transparent table in the test, with one string connected to a flower and another was detached. For further details and descriptions of each experiment, see the text.