I love watching the bumblebees work the milkweed flowers. They are so systematic in the way that they probe into each chamber of the flower, moving along using their front legs to separate the chambers and dipping an antenna in occasionally to check for scents left by other foraging bees. On a recent morning, I got up in the bumblebee’s face with my macro lens while the bee probed the flowers, hoping to catch the action of their tongues as they lapped up the sticky syrup.
Bumblebees use their tongue, which extends from that long sheath, to mop up nectar at the base of a flower. Generally, the larger the bee, the longer its tongue is, which allows bees of different sizes to specialize on differently shaped flowers.
I’ve always been curious about how bees “decide” whether a given patch of flowers is worth an investment of their time to probe for nectar. Bumblebees (and perhaps a variety of other bees as well) mark the flowers on which they have spent considerable time foraging (i.e., rich nectar reward) with a scent that indicates it has already been tapped. As the scent decays over time, presumably the nectar reward builds up again, resulting in more visits from foraging bees.
I never did get a good look at the mop end of that long tongue, but I certainly have a new appreciation for bumblebee faces.