This decorative fruit fly trap is a nice alternative to having a glass with plastic wrap on your counter top. This improved design builds on two previous designs by allowing more vinegar vapors to be emitted. It includes an insert for your attractant. 

For the attractant, I use apple cider vinegar with a drop of soap. The apple cider vinegar attracts the fruit flies and the drop of soap drowns them by reducing the surface tension. 

Included is a cylinder that you can use as an insert. The insert must be printed in vase mode.