For fruit flies in kitchen put some apple vinegar in a
cup, cover it
with saran wrap, make a few small holes in it with a knife and push
the wrap into the cup (not touching the vinegar) to make a dimple.
Works perfectly.
We use 2 parts molasses to one part apple vinegar. You
don't even
need the saran wrap!
People who have never actually tried doing it constantly claim that you
can catch more flies with honey than with vinegar.