Hummingbird Clearwing Moth On Butterfly Bush

This Hummingbird Clearwing Moth seems to like this Butterfly Bush. It keeps coming back, day after day, spending about  5 minutes at a time. I cannot get very close, otherwise it flies off, so I am about 15 feet away. I am using a 400mm lens, with a 1.4X teleconverter, on a Canon 1.3X crop camera body. After adjusting files in Adobe Camera Raw, I use a fairly severe crop. Even so I thought they came out with quite a bit of detail. I also had to use a High Shutter Speed with a High ISO to stop the wing movement as best I could.