Our fall-colored mystery bug last week was a newly-molted boxelder bug.
I thought some of you might have noticed the cast exoskeleton right behind it. 
After a few hours, it would have looked like this.
Boxelder bugs overwinter as adults, so the mystery bug was getting ready for winter.
Let me know if you would like to see more mystery bugs.
I enjoy your mystery bug posts, although I’ve never been able to guess any of them.
Tiffany,
Thank you for taking time to let me know. I’ll be sure to include some more in the future.