Now this won't work too well for a whole mess of large shells, but you might try it for a few smaller ones. I've heard of just putting them out by an ant hill and covering them with an old piece of cloth (protection from the sun). What you have to do is determine whether your ants are carnivores or herbivores. Some are both. If your ants have been properly styarved, they will do a quick and thurough job. Then you have to figure out how to get rid of the ants before company comes. Art