Old B/W horror movie

[radad]

I remember watching a horror movie on tv that involved people hiding a frog looking mutant in the attic. The movie used tacky special effects like a scene where the actors encountered bats that were obviously on strings. At the end the mutant was revealed. Can anyone give me a guess as to the name of the movie? Thanks

[Ferox13]

Don't remember the bats but The Maze has a frog like guy in oit