Trophallaxis is the direct transfer of food or other fluids from one insect to another. It is especially common among the social insects such as bees, wasps, ants, and termites. In many species, including bees, trophallaxis is an important part of colony communication.
While fluids such as nectar, water, or royal jelly are being transferred between bees, important information is transferred as well. For example, workers who have licked the queen pass on some of the queenly essence to other bees during the exchange. Not only does this inform the colony that the queen is alive and well, but it also suppresses the development of ovaries in worker bees. Trophallaxis is also used to distribute information about new nectar sources or about feeding conditions inside the brood nest.
The fluid is transferred through the proboscis, a straw-like tongue used for sucking liquids and also for tasting. Although it may look smooth and uniform, the proboscis is actually quite complex, composed of several different parts. You can think of it as a tube within a tube. The outer tube is useful for sucking in large quantities of liquid such as water or honey. The smaller tube inside the larger one is used for collecting tiny amounts of liquid such as that found inside flowers. This tube is equipped with a hairy spoon-like tip that helps to mop up the small drops of nectar. The tip also has taste receptors.
In honor of Valentine’s Day, Zachary Huang, a professor of entomology at Michigan State University posted an amazing set of trophallaxis photos. He has captured images of one bee feeding one, two, three, four, and five other bees simultaneously–all of which appear to be kissing. The photos were taken in Australia (watch out for those Australians!) during one eight-minute period. Be sure to have a look. Other great bee photos by Zachary can be found throughout his website, Bee the Best.