Lesser organisms and the smell of fear

So lately, remnants of my brother staying at my apartment have resulted in the proliferation of fruit flies. I would say somewhere on the order of 10-20 fruit flies resided in my apartment over the last two weeks. I finally decided to get rid of them.

Apparently, you can use red wine vinegar (it has to be red wine vinegar so it's like a fermented fruit) in the bottom of a bottle to attract fruit flies. You pour some into a bottle with a small neck, and the fruit flies fly in and eventually drown in the vinegar.

Anyway, the attracting part was working, but I was getting impatient for the drowning bit - and the flies were sort of hanging out on the outside of the bottle. So I decided to speed up the process by taking a ziploc bag, opening it, and then putting it on top of the bottle so that the flies would fly into the bag, at which point I would take the bag, close it, and squash each fly caught.

The first 10 or so were easy. However, after that, it got harder and harder to catch them this way.

I wonder if they can smell the death of their fellow fruit flies. I wonder if they smell the fear of other flies trying to escape being squashed, and that's why they fly away with more urgency (because sometimes, they just sort of hover, other times, they jet!).

Anyway, it's been a great challenge killing these fruit flies. I think there are still three left.