What are jar flies?

"Jar flies" is not a recognized scientific or common name for any specific insect. It's possible that this is a regional or colloquial term used to describe a particular type of insect.

To help identify what you're thinking of, can you provide more information?

For example:

* What do they look like? (color, size, shape, wings)

* Where do you see them? (indoors, outdoors, near water)

* What do they do? (fly around, bite, make noise)

* What time of year do you see them?

With more details, I can better understand what you're referring to and potentially identify the insect you're asking about.