Location: Trenton, ME
We have been at the campground outside Bar Harbor for several days, and I have periodically seen black and white insects slowly drift into my field of view and then vanish. They were about half an inch long, with striped legs, and would move almost as if they were suspended from a thread.
It turns out they are Phantom Crane Flys (Bittacomorpha clavipes), and because they have huge (relatively speaking), concave pads on their feet they are able to catch air currents to "float" for short distances. Once they fly into shade, their coloring makes them very difficult to see, hence the "disappearance," and the name "Phantom."
For several days I have been trying to get a good photo of one, but as soon as I'd see one it was gone. One even landed on my leg while I was doing laundry, but I didn't have the camera with me! I finally got this one today:
Pretty interesting insect! Its range is the Eastern U.S. and Canada.