I know how to kill them. I know how to kill them "organically". I'm ashamed to admit I even know how to cook and eat them. Yes, it's more than a little bit survivor-woman, but it was a bad day and you should have seen what they did to the impatiens. Overnight I tell yah! Still they live. I don't kill them. I don't cook and eat them and wouldn't even if I ate meat because the process involves skimming snail scum off the pot of boiling snailyness for an hour. With all due respect to French cuisine, I myself cannot do that, nor can I feed them for weeks on cornmeal like they were my little friends when what I'm really doing is cleaning out their insides before I toss them into that pot of boiling water..
Instead I pick them off my holey hydrangeas and throw them over the fence. I know they come back.
I've been tempted to put a dot of fingernail polish on their backs to verify that they come back, but haven't as yet. I just don't have it in me to make something suffer if I can keep from it. It's hard not to go in and get the salt, especially when you look at them eating your hydrangea and swear they're saying, "Almost done here" knowing full well they're eyeballing the maidenhair fern.