Food grade instant fly killer

This is a cost effective, more convenient improvement of my previous fly killers.

Two squirt of food grade liquid soap, such as Dr Bronners, or just any soap/detergent. Mix with 40% or less alcohol. Vodka is 40%. You can find rice wine approaching that at a lower cost. Or you can just dilute with water cheap first-aid rubbing alcohol at 70% or 90% to 40%. 

Ideally you need a spray bottle that can deliver a strong narrow conic stream at one to two feet. But most bottles will do.

Previously, a little soapy solution can stop flies flying, or they have to stop nearby. Diluted alcohol can do the same. So combining them is a good thing.

Previously, I find that only 70% alcohol can kill flies almost instantly. They are struggling a bit but cannot move far and will die soon. Diluted alcohol can also kill but seems to be slower. Adding soapy solution seems to increase the kill speed. I tried 40% but I think lower concentration will be sure kill too.

I woke up in a heat wave and killed 4 flies at the patio door.