Them! (1954)
Them! is a 1954 Warner Bros. Pictures black and white science fiction film about a nest of gigantic irradiated ants discovered in the New Mexico desert. The film is based on an original story treatment by George Worthing Yates, which was developed into a screenplay by Ted Sherdeman and Russell Hughes. It was produced by David Weisbart, directed by Gordon Douglas, and stars James Whitmore, Edmund Gwenn, Joan Weldon and James Arness.
More at Wikipedia.