This is a Hummingbird Clearwing Moth, also called a Hummingbird Sphinx Moth. It's feeding on the nectar of a Monarda or Bee Balm. Using it's long proboscis to probe deep inside the flower, it feeds while hovering in flight. The side to side flight maneuver is called 'swing hovering,' a talent evolved only three times and only in nectar eaters: bats, birds and insects. Elephants do not do this, nor do any people I know, though I'd love to meet someone who does. It's an example of classic convergent evolution, when unrelated species have developed the same biological traits.
This moth's wing span is about two inches, pretty big as insects in Maine go. Sphinx moths are the fastest flying insects on earth and having been clocked at 33 MPH! I don't know who figured that out, nor how. Were they raced around a closed track, wearing little saddles? Was some fat guy smoking a cigar standing by with a stop watch and a racing form? "And they're OFF!" shouts the announcer as the gate snaps open. "It's Bizzy Bee on the inside, Hairy Hummer in the rear, Sticky Stan pulling into the lead!" I can smell the horse manure and dust...........snap out of it! These moths have never been confused with horses, to my knowledge. But, they are commonly mistaken for hummingbirds, thus the common names. Each year, someone tries to tell me that they are hummingbirds, which I consistently can demonstrate through photographs to not be true; many races are decided by a photo finish.
The moth's proboscis extends as much as two inches to get to the nectar.