Oh my god. I have heard that snakes can follow the trail of other snakes to find spots to hunt and build dens. Maybe you have to eliminate the trails? I know they hate the smell of ammonia and mothballs...
On a funny note, when I googled this the first suggestions were "get rid of the food source and eliminate any standing water"... well, maybe not so funny after all!
On a funny note, when I googled this the first suggestions were "get rid of the food source and eliminate any standing water"... well, maybe not so funny after all!