I Guess I'd Better Get my Eyes Checked

I had this idea to catch a bunch of fireflies in a canning jar, then remove the lid and take a picture of them as they leave. There's a slight trick to it. Fireflies aren't always lit up: they twinkle. So you spot the twinkle, then track them and snatch them. I see the twinkle, I track them, then they fall out of my visual range (dang bifocals). Only caught one in ten minutes. There goes THAT picture idea!