Honey bees that collect water are specialists, a set of foragers completely distinct from nectar gatherers. It’s all they do!
This job, however, only begins for them at the mature age of 20 days. Prior to that time, they perform other duties in the hive. As water collectors, they fly out to find a source, and then transport water in the same “honey crop” as nectar foragers use, so on every foraging trip, they can carry a volume of 1/250th of a teaspoon (50 microliters).
A colony requires water to quench the thirst of individual bees, to cool and humidify the hive in summer months, and to prepare food for the brood (and the queen!)–a need which is particularly acute in the spring. The thirstiest time of all may be in January, when the colony is living on stored food, which requires a good bit of water to be added to soften or dissolve the sugar, crystallized honey, or bee bread so it can be swallowed and digested easily.
When a water forager selects a source—a puddle, a pond, maybe droplets on a leaf at a distance from 20 feet to a mile or more from the hive—she visits that same spot over and over again, and lands on exactly the same pebble or other platform every time.
It is not necessarily clear, clean, pristine H2O that honey bees collect. Rather, they choose water that contains the minerals and nutrients required in the hive at that particular time. The source may look muddy or green to us, but the bees know just what they need and where to find it.
The water foragers deliver each precious load to particular workers in the hive, sometimes called water spreaders, whose only job at age 10 to 19 days is receiving and distributing water for all of the colony’s needs. They start and stop their foraging activity throughout the day according to conditions within the hive.
Between bouts of gathering water, the foragers wait quietly in the hive until needed again. As demand for water increases, these bees employ the same “waggle dance” to recruit and convey information to others who serve in the same capacity, just as the nectar and pollen gatherers do for their own recruitment activity.
The water forager’s role has been shown to be at least in part genetically predetermined.1
Dr. Tom Seeley conducted extensive experiments on this topic of water foragers, published in 2016.2 You can view an accessible and delightful video presentation of his findings at https://www.youtube.com/watch?v=bb5cowu-NZI.
1Seeley, T.D. (1995): “Which Bees Collect Water?” Section 9.3 in The Wisdom of the Hive—the Social Physiology of Honey Bee Colonies, Harvard University Press, Cambridge, Mass.
2Ostwald,M.M., M.L. Smith, and T.D. Seeley (2016): “The behavioral regulation of thirst, water collection and water storage in honey bee colonies,” The Journal of Experimental Biology, 219: 2156-65 (https://journals.biologists.com/jeb/article/219/14/2156/15394/The-behavioral-regulation-of-thirst-water).