I read about using a strong caffeine treatment to kill slugs an snails several years ago. I half heartily tried to use it in my vegetable / trial garden several years ago. I did not notice any results but, I was not being diligent either.
Last year, I wanted to try it again and was surprised that now you have to work hard to find, and purchase powdered caffeine. Too many people took MASSIVE, MASSIVE doses and overdosed and received their Darwin Award so, purchasing the powder is getting difficult.
Anyhow, I got a supply and started using it this week in the garden… just with a squeeze-bottle.
I mix up a small batch on the stove to dissolve the powder and, I pour it into the squeeze bottle after cooling or diluting.
My snail and slug population is dropping fast… See one, squirt one.
I set aside a bunch of snails and slugs I treated and only one was alive after eight hours. By the end of the day, it was dead too.
I am also going to try the 0.1% solution as a repellent this year.