Where have all the garden snails gone?

“For several years now, we have not seen any snails.  We used to be inundated with them. Neighbors near and far in Torrance have noticed the same thing. What happened to the snails? Is it a bad omen for us? I challenge you to find out what happened to them.” – Nancy Ingraham
I accept the challenge and would appreciate a communication from anyone reading this who has experienced a similar decline in snail visitors so that we can map the phenomenon.
I have learned that there