Wow! So many kind responses! About the size of the juvenile C. lubrica; I was real tired last night, and I just made a crude (and totally inaccurate) estimate. They are really about 3mm. I will try some various greens, but, like Kurt said, they might feed on microalgae. It would be interesting to find out their diet. I have plenty of eggshells, and I will just put them in the blender and set it on "liquify" to make powder. That thing about lubrica living in leaf-filled gutters is neat; I saw a few VERY TINY (1mm) specimens on the undersides of dead leaves the other day; the leaf could be like a sail, and be blown up on the roof with the snails on it. Anyway, I give my thanks for the help you all provided; I will keep everyone updated on the snails' progress. Kind Regards, James