[warrgazur]

Viable eggs hatch in a few weeks.

Well something is going on then, as I had ducks that loved eating the snails, these were fenced in, as the foxes loved eating the ducks. Anyway, they were very effective at eating all snails from their enclosed area, but other small snails continued to emerge for several years despite their efforts. Some snails moved in from outside, but these did not last long.

By the way, I no longer live in these calcareous sands and moved to the snail free, acid soil heathland where bio-diversity is much higher.

As for predators, there may have been some, but the numbers of snails are so high that they had no affect. To control them would need vast numbers of something like microbes or fungi.