I don't know what it is about purple coneflower that bumblebees find so attractive—but I never find one without the other. Perhaps the bloom's nectar is especially tasty or intoxicating, or the pollen especially delectable. Even though there may be a half-dozen other flower species of similar height and size in full bloom nearby, the bumblebees seem most interested in snuffling over the flower's rounded centers.
Up close, they look for all the world like shaggy beasts grazing a reddish-orange field. Which is exactly the case.
Bumblebess forage to gather both nectar and pollen. In the photo above, you can see a only few grains of pollen clinging to this particular insect's rear legs; often the legs, sides, and underparts are practically covered with the stuff, as if they'd been heavily dusted with golden flour. Bumblebees use the gathered pollen to feed their larvae young—and of course they inadvertently pollinate various plants and flowers as they forage, making them one of the most useful garden helpers around.
Because of their large size and loud buzz, bumblebees tend to frighten some folks who don't understand their gentle nature. I suppose they do look a bit fearsome, unless, like me, you equate them more to woolly-haired sheepdogs.
However the truth is, a big ol' bumblebee hummin' and bumbling its way around your plants—even those plants inches away from where you stand or sit—poses no threat whatsoever if left to its business. Yes, they can sting, and more than once since their stinger lacks a barb. But they won't…not unless you threaten or try to harm it in some way. In point of fact, a bumblebee will pretty much do everything it can to avoid any sort of contact with a human, and any fear we have towards them is largely unfounded.
This morning, though the day is arriving heavily overcast and threatening rain, the bumblebees have already made their first visits to my small patch of purple coneflower. "Busy as a bee" applies to bumblebees as well as honeybees. They may be fat, but they're not lazy.