For how long will the DIY mosquito spray last?

http://myhousepests.com/mosquitoes/homemade-mosquito-yard-spray.html

Hi Paula. I'm Cindy. I did a bit of reading so that I could answer your question properly. Most DIY mosquito repellents are good for 3 - 4 months. I read the list of the three ingredients (mouthwash, Epson salts, and stale beer) and I think these ingredients would last a lot longer on their own. I also read that this recipe keeps all kinds of insects out of your yard for at least 2 months. Good luck with this Paula. Keep us posted on how it went for you. Best wishes being sent your way.

I would make a new one each season.