I suspected that that might be the case so I use tweezers to remove the snails from the pot _before_ I crush them.
I can get metaldehyde baits here is California. I was looking for a less toxic alternative but if the Physan idea does not pan out then I will be back to considering metaldehyde baits. If I use metaldehyde bait then I would like to do so as judiciously as possible. Can I put just one or two pieces of bait in a pot and expect that the bush snails will quickly find it? Does anyone know of a brand of metaldehyde bait that they find especially attractive to bush snails?
I experimented to refine my estimate of how long the snail has to remain in the 400 ppm AI Physan-20 solution for mortality to occur: 15 minutes was not enough but 60 minutes was.
How about acephate; has anyone experimented with its efficacy against bush snails?
Here is the paper that got me to experiment with SA-20. See table 1 on page 4.
http://wet.asu.edu/Biological%20acco...r%20snails.pdf