Folklore - When did society start and stop believing in, Vampires, Werewolves, Witches, Mermaids,?

Really legends of this kind never really go away they just evolve and change with societies. We have a need as a species to explain the unexplained and when no such explanation exists some people revert to our old ways of thinking. Our tendency to believe in such things seems to have a lot to do with society around us. As for here in the United States ghosts never really went anywhere, just how people thought of them. When my grandfather was a boy living in a remote area of Florida in the 1930's they believed in ghosts but then some strange things went on in that area. Some stories about panthers and ghosts were spread around to keep people out of certain areas where moonshine stills were hidden. You'll notice I mentioned panthers, that is because at that time period belief in ghost while still present was not as prevalent and people where more likely to believe it if you told them a man eating panther was stalking the woods. However some of the stories that were spread around at that time were as a form of entertainment and some people just took them to heart. Some people are just superstitious, I'd say that belief in these things become less prevalent when we live in closer proximity to one another and information that disproves such things is more prevalent. I think if there were a catastrophe where we reverted to a more primitive way of life and were back in the wilderness belief in spirits would become more prevalent. When you are in an environment where you don't feel safe your mind is on high alert, you start jumping at shadows and seeing ghosts, vampires and mermaids.