Them! (1954)

In director Gordon Douglas' paranoic mid-50s creature feature:

• the scene of police finding a traumatized girl wandering trance-like, near a smashed-up automobile, and blood (but no bodies)
• after she was revived out of her shocked state from a whiff of formic acid, her scream of: "THEM! THEM!!!! THEMM!!!!"
• the scenes of the giant radioactive ants (due to atomic testing in the New Mexico desert) with mandibles on the loose
• the discovery of their nest