Do you know the name of this movie? It's a 70's sci-fi flick that involves a strange planet and giant ants...?

All I know is what I'm recalling from childhood so my clues may be a little vague. A spaceship from Earth crash lands on a planet. Maybe the moon? As a couple of people go for a walk to see what's out there, they come back to find their ship has been dragged away by something to a cave system where these ants (?) are controlled by a giant sphere. But once the sphere stops, they stop. I know it's strange but it's doing my head in trying to remember! Please help!