When I first saw it, I registered "large dark butterfly constantly flapping while feeding" so I thought it would be yet another Giant Swallowtail (which have been fairly common up around Ottawa for the past few years.) But I try to always get an id photo to help me remember to document what I've seen, so I went closer to take a pic. Then the sun shone off it making the wings as blue as a Morpho. They are a really pretty butterfly.
My brother has seen them a few times but not this year yet. I don't know if this is an incursion year or if this was just a single adventurer.
