How to keep snail out of the kitchen?

Answer 1

You need to figure out where they are coming from. Most likely there is a gap somewhere in the wall or floor. Fix that, then purchase an iron phosphate based snail and slug killer and put several small piles of it around your problem areas. The critters are attracted to it and eat it. They get full from it and stop eating, causing them to starve to death pretty quickly.

Answer 2

Spray or pour beer in areas where snails usually are. They like to consume beer, but it dehydtrates them and kills them.