Mix about 3/4 cup of lemon juice (from the bottle), about 1/4 cup of cayenne pepper powder (fresh), 1/2 cup of liquid dish soap with 2 cups of water.
Pour this into a spray bottle but strain it first with a fine screen so the pepper won't plug up the spray bottle.

When outside, lift the spray bottle above your head (observe wind direction firs) and spray them little bastards. When one gets hit with only one puff of mist, it is dead within ten seconds.

If the mist gets into your eyes, it will sting a little, so close your eyes when you spray above your head. Let the wind carry the mist where they are hovering.

Amazing to watch. It is your turn to torture them!

Experiment yourself. Let inside some and see how little is needed to kill them.