Well, I think a mystery is solved. For some unknown reason, Dolly has been very, very eager to go outside at 10 PM every night. She bounces to the door and waits to be let out. Then she is out there in the dark for quite a while, and eventually comes back in extremely excited about whatever she was doing, bouncing around happy and exhilarated and pleased with herself.
Well, yesterday when it was still light I saw her poking her nose through the fence repeatedly trying to get something. When I went to see what it was, it was one of those locusts that will climb out of their skin and leave a brown shell behind. This one was on a piece of grass, and she finally got it and ATE it. I couldn't tell if it was a real locust or just the shell. Then I found an empty shell not far away in the grass and showed her and she jumped on that. So I wonder if she has been going out and...eating locusts? Don't think I've ever had a dog do that. Maybe that's why she was so excited, she was going out "hunting" and finding FOOD.