Some Responses of Honey Bees to Alfalfa Flowers

For honey bees the alfalfa flower is a trap. When the flower trips the space in the corolla is closed, and if the space is occupied by a bee's proboscis the bee is caught and must free herself. Most nectar-gathering honey bees avoid tripping and the trap by inserting the proboscis at one side of the flower. But certain "nectar-tripper" bees used a simple method of inserting the tongue directly into the corolla where the trigger is located. Tripping frequently occurs. The subsequent struggles of the bees are described and shown in photographs. Nectar-tripper bees were rarely seen in the field. But under conditions designed to eliminate experienced field bees the proportions of trippers observed was greatly increased, so that 128 were identified and observed in cages. About half of these furnished fragmentary data, of the other half, a third changed to the side approach. The others failed to change or were not observed after changing. The change in approach to the flowers was accompanied by a drop in tripping efficiency, improvement in habitual use of the new method and an increase in working speed. For bees that failed to change, tripping efficiency varied up or down, habitual working patterns remained variable, speed remained low, while fixations for withered and tripped flowers appeared occasionally, and nervous behavior was general. Learning and the development of skill were indicated for those that changed. Field experiments on nectar bees offer confirmatory evidence. The tasks of a pollen-gathering honey bee are more complicated. She must trip the flower, then extricate her proboscis from the trap before collecting the pollen. Day to day histories were acquired on only two pollen-gathering bees. Both of these showed higher tripping efficiency on the second day than the first but no further progress. Some pollen bees had difficulty with the trap but as a group they extricate their tongues with ease contrasted to the repeated struggles of the nectar-trippers for freedom. In speed, the range in flowers tripped per minute compares to the range of flowers visited per minute by side-workers plus nectar-trippers. Learning processes are indicated in the activities of alfalfa pollen bees.