A couple of fly boxes JAM-PACKED with flies apparently feel out of my fanny pack. I didn't discover this until the next day. I went back and searched the area, but it was a public area, and the boxes were never found.
Now I try to put my address label and maybe my phone number on the inside of the lid of all my fly boxes. At least then somebody has a legitimate CHANCE of returning them to me if I lose them again.