The BBC reports on the possibility that garden snails have a homing instinct and will return whence they came. So perhaps chucking them over the fence into the neighbour's garden is not enough! This idea comes from a 69 year old gardener who noticed them returning to eat her veg even when she removed them up to 10 metres away. A mass experiment is being arranged via Radio 4 to test the theory.

Personally I suspect that the snails don't home in specifically, but that they wander randomly over a large (e.g. 10 metre) range and hence will tend to find your petunias again eventually. But that's very different to the suggestion that they might make a beeline back to their start point.

It's just bucketed it down here and there are a crazy number of snails cruising across my garden path. Perhaps they're all sprinting back home after the lengthy dry spell?