Simple fruit fly trap.

I know there are much better (with threaded tops) traps out there but this was one of my first prints so I thought I'd throw it up.
Basic fruit fly trap - works with most wide mouth canning jars in conjunction with the canning band.
[EDIT}
Ok so after employing my own trap two things became apparent to me:
1. There is too much surface area around the opening to the trap. They flies are perfectly happy just hanging out on top.
2. The reason I think they are perfectly happy to