I have some fruit flies in my kitchen. A few of them starting flying around my living room, so I decided to set up a trap. I put out a bowl of apple cider vinegar and put some drops of dish washing soap in it. An hour or two later, I come out to see a pile of dead fruit flies at the bottom of the toxic soup. I also noticed many of them perched on top of the bowl, others go down into the bowl to the very edge, and run away up to the top. I washed out the first batch of dead fruit flies and repeated the process. This time, I placed some ripped up banana peels in the soup. There are some more dead flies, but there are still some just perched on top of the bowl or congregating on my paper-towel rolls. Are the flies perched on top, or who are running away 'smart' enough to know that a toxic trap awaits them?