The Black Scorpion.

A volcanic explosion releases an army of gigantic man-eating scorpions. Now the fate of mankind rests on the shoulders of Hank Scott (1950s monster movie stalwart Richard Denning) as the creatures rip a train from its tracks, snatch a helicopter from the sky and, in the film's most gripping sequence, battle each other in their subterranean lair. Incredible special effects by Willis O'Brien (the original "King Kong," "Mighty Joe Young") highlight this classic sci-fi entertainment.