should keep you out of the poison aisle.
1. Just put a bit of fruit, this one has grapes, in a jar with a bit of
balsamic vinegar.
2. Cover with a double layer of plastic wrap and rubber band
as a lid.
3. Use a pin to poke holes into the plastic wrap.
4. Place indefinitely where you have a gnat problem.
The bugs will get in easily, but will be stuck.