Later in the evening, I went out, and their were a lot more of these flying around the vines. I counted at least 10 at one time (and more were flying in), which is the most I've ever seen at one time.
Since it was darker out, the images didn't turn out so well:
Because of the way these feed on flower nectar, and because of the way they move, people seeing them from a distance often mistake them for hummingbirds. While I was out photographing these during the day, I looked up to the top of the vines, and saw this!