powered by AFI
Copyright records state that the film was shot in Eastman Color, and contemporary Hollywood Reporter news items and production charts reported that shooting was in 3-D and WarnerColor, but the final film was shot in black and white. Only the letters in the opening title card were in red and blue, over a black and white background. According to a September 1952 Daily Variety news item, Warner Bros., which had released the successful The Beast from 20,000 Fathoms, was eager to make another science fiction film and paid George Worthing Yates $25,000 for his story about giant ants in the New York subway tunnels. A July 1953 New York Times article announced that Russell Hughes would write a screenplay based on Yates's story and Ted Sherdeman would produce it. Later, Sherdeman took over the completion of the script from Hughes and David Weisbart became the film's producer. According to modern sources, the New York locale of Yates's story was moved to the New Mexico desert and the Los Angeles River tunnel system to cut production costs.
According to a modern source, Warner Bros. studio technician Dick Smith designed two full-sized models of giant ants, which were controlled by ropes and pulleys, to interact with the actors. Film footage of smaller models and real ants, enlarged to appear nine to twelve feet long, were intercut with the rest of the film, according to the same source. Hollywood Reporter news items and production charts reported that the film was shot on location in the Mojave desert, near Palmdale. Modern sources identify Los Angeles' Tujunga Wash as the location of the river tunnel scenes. Although their appearance in the film has not been confirmed, November and December 1953 Hollywood Reporter news items add Lloyd Dawson and Charles Meredith to the cast. James Arness, who played FBI agent "Robert Graham" in Them!, was being considered for the lead role in Walt Disney's Davy Crockett television series when, according to modern sources, Disney saw Fess Parker's performance as the Texas rancher in the film and offered him the part. Despite its small budget, Them! was well respected by the critics and became Warner Bros.' largest grossing film of 1954. Modern sources credit it as the first "big bug" movie. It received an Academy Award nomination in the Special Effects category.
According to a September 1955 Daily Variety news item, Dr. John B. Grant of the Rockefeller Foundation filed a federal suit against Warner Bros., asking $200,000 for allegedly invading his right to privacy and ridiculing him in public by using his name and likeness in his professional capacity. The outcome of the lawsuit is not known. According to an October 1999 Daily Variety news item, Artists Production Group, an arm of AMG, planned a remake of the film, which was to be written by Mark Montgomery and directed by Joe Johnston; as of spring 2005, the picture has not been made.