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 hang out on top is because I printed mine with a low fill factor leaving it quite permeable to the aromas of the fermentation happening below.

I have uploaded a new polygonal design that eliminates most of that surface area up top. I went with a polygon because it's a faster print for my machine (Micro 3D) and at the moment my machine doesn't like circles so much (backlash issues I have yet to solve).

I do have a round version if you'd prefer that.