Having captured this shot of a forager working in a Phacelia bloom, I was inspired to further study the functions of her antennae. One of my favorite resources is Honey-Maker by Rosanna L. Mattingly, and here is some of what I learned:
Her antennae are made up of three segments, the Scape, the Pedicel, and the Flagellum, and she moves each of her antenna using four muscles inside her head that rotate each Scape (and thus the rest of her antenna as well).
Each antenna has thousands of sensors through which she can taste, smell, detect vibrations, measure textures, and learn about other conditions in her environment. In addition to muscles, each antenna has a nerve and also branches of small breathing tubes known as tracheae. And all that in each tiny antenna!
She uses her antennae to communicate with others in the colony through an interaction known as antennation. For example, she may touch another worker's antennae with hers in order to ask for food. The contact between the antennae of the two bees is believed to help them arrange their mouthparts for the transfer of food.
The sensors for smell in her antennae are used both inside and outside the hive. Inside the hive, for example, she can detect the scent of a dead bee (the smell of oleaic acid) and thus know to remove the bee. Outside the hive she can detect the fragrances of hundreds of different kinds of flowers, finding the blooms she was just recruited to find by a dancing forager in the hive. In addition, the sensors for smell in her antennae allow her to recognize all of the pheromones produced by her colony.
Another cool thing about her antennae is the Johnston's organ. This organ is located in the second segment of each of her antennae, the Pedicel. With it she detects vibrations, which we would interpret as sound, as each Flagellum responds by moving with those vibrations. And, because this organ enables her to detect changes in her antennae's position, it helps her to measure her air speed as her antennae bend in response to air flowing over them.
Finally, her antennae also relay information about carbon dioxide concentration (a factor in attaining a state of torpor in the winter cluster), temperature, and humidity.