I used the Hot Shots hanging fly killers from Walmart -was in a single hanging white piece of plastic. You just hang it where the fruitflies are and that's it. It said for outdoor use - so I opened a window and made sure there was no food out. Within an hour they started dropping all over dead. Only needed it in the house for 1-2 days and they have been gone since. Hung it outside my kitchen door after.
Used this after nothing else was working.