Bombus impatiens is one of the more common North American bumblebees, it can be found in Ontario, Maine, Georgia, Kentucky, Maryland, New Jersey, New York, Pennsylvania, South Carolina, Virginia, West Virginia, south to Florida, west to Michigan, Illinois, Kansas, Missouri, Wyoming. Body lengths, queens 21 - 23 mm, workers 9 - 14 mm, males 12 - 14 mm. Their hair is short and smooth, and they nest underground. Queens can be seen from April, workers from May, and males from June. Favourite flowers include thistles, and goldenrod.
Above you can see a B. impatiens worker with her tongue extended. There is no flower, so she is probably licking up honeydew excreted by aphids. B. Impatiens has a medium tongue length, for more on the importance of tongue lengths and the tongue in general visit the bumblebee tongue page, yes, there is a whole page devoted to this!
The photograph on the right shows the typical pose of a bumblebee who is not happy about something.
In this case it is probably the closeness of the camera, or it could be human breath (they don't like mammal breath), or both. The raising of one of the middle legs is always a sign to back off - the bumblebee won't sting, but it is disturbed by your presence.
Quite often if you back off and then move closer very slowly they will tolerate you. Also it is a good idea not to breathe too heavily, or to breathe to the side as mammal breath is not something they like. It is an instinctive thing as the only mammals that get this close are ones that are about to eat the bee or break into its nest.
Below is a photograph of mating. The queen is in front and the male behind. Males are usually smaller than queens. There is more about mating on the mating page.