The Caterwauling Charm (incantation unknown) is a charm that warns of intruders in an area. When cast, anyone entering the affected area will set off a high-pitched shriek that echoes and tears at their nerves. The Death Eaters cast this spell over Hogsmeade during May of 1998 as an added precaution after a number of students announced open rebellion. It was mainly, however, to warn them in case Harry Potter came to Hogsmeade, which he did with his acquaintances Hermione Granger and Ron Weasley.