Two more Greek snake stories--
The island of Andros (I think it's Andros), every Aug. 15, little snakes with crosses on their heads appear, no one knows from whence, and go to the church. They're totally harmless, but don't like crowds. After the feast, they go back home.
On another island, another snake found its way into the chalice and died. The pious priest, when he was finishing the Holy Gifts, did not want to throw out the snake, since he had mingled with the Holy Gifts, so he cut it up and ate it, all the while cursing the snakes on the island. All the snakes on the island then died.